This recipe yields about 8 pints of salsa, but this can vary depending on the water content of your tomatoes and how thick or thin you make your salsa.

Here is a short glossary of basic canning terms:

Band: A metal, threaded screw band used with a lid to form a two-piece cap.
Boiling-Water Canner: A large pot or kettle big enough to completely immerse filled jars; used to process jars.
Headspace: The unfilled area between the rim of a jar and the top of the contents of that jar.
Lid: A flat, metal vacuum sealing lid used with a band to form a two-piece cap.
Processing: Sterilizing jars and their contents in a canner (a boiling-water canner, in our case) to destroy any bacteria or enzymes that may harm you.

Step 1: Gather Ingredients and Supplies

Gathering all of the necessary ingredients and supplies before you begin will save you time and make the canning process much smoother.

You will need the following ingredients and supplies:

Ingredients:
Approximately 15 lbs. of tomatoes (this is about 3 quarts of prepared tomatoes)
3 cups onion
6 jalapeño peppers
3 cloves garlic
2 cans tomato paste (12 oz each)
2 cups lemon or lime juice
1 tbsp salt
1 tsp pepper
1 tbs sugar

Optional: Cilantro, cumin, and any other peppers. I used banana and hot chile peppers that I grew myself, plus an ancho chile - different combinations of peppers will give you different flavored salsas, so be creative. Just be sure you taste it as you go - you don't want to make it too spicy to eat and share!

Supplies:
large saucepot (the bigger the better - keep in mind that we'll have around 3 quarts of just tomatoes)
small saucepot (This is just to keep the lids in, so size isn't as important)
canner or large stockpot (This is what the filled jars will process in)
large stirring spoon
three large bowls
pint jars
lids and bands
towel
ladle
timer
ice

You'll also want to either have your trash can handy, or another bowl to use as a trash bowl - this will make getting rid of the skins easier.

Note:
It is very helpful to have canning utensils, such as a jar lifter, lid lifter, wide-mouth funnel, and headspace tool. However, if you do not have these, you can use tongs (to lift jars out of the hot water), a fork or a magnet (to lift lids out of the hot water). Just be very careful not to drop your jars!

*I know that sounds excessive, but we're going to be getting rid of the skins, the seeds, and squeezing a bunch of juice out of them.

Step 2: Set Up Your Workspace

Before you start canning, it is important to have your workspace set up so all of your supplies will be ready when you need them.

First, your jars and lids (don't worry about the bands) must be hot when they are filled - this is very important!

Keep your lids hot by keeping them on the stove in a small saucepot filled with simmering water. You can keep the lids simmering until you are ready for them - just do not let the water come to a hard boil, as this could damage the seal. I usually keep the pot with my lids on a back burner so they're out of the way.

You can keep your jars hot one of two ways. You can place your empty jars in your canner or stockpot with enough water to cover them by about two inches, and let this water (and the jars) boil until you are ready for them. Or, you can load your dishwasher with the jars (no other dishes at the same time, please!) and let them run through a regular or "sanitize" cycle. Your dishwasher will keep the jars hot until you are ready to use them. If you choose the dishwasher method, you should still fill your canner or stockpot with water (enough to cover jars by 2 inches) and bring the water to a boil (with the lid on) so the water is ready for processing once your jars are filled. I usually put a few more jars in my hot water bath or dishwasher than the recipe calls for, just in case I end up with more product than I expected (which happens frequently). For example, this recipe should make about 8 pints of salsa, but since it can vary so much, I'll probably have a whole case of jars ready, just in case (just don't forget the extra lids, too!)

Lay a towel down over your countertop. This is where you will place your jars during filling and after processing. It catches any drips, but also protects your jars.

Step 3: Prepare Your Tomatoes

The tomatoes you use should be able to stand up to the canning process. Good varieties to use (such as Roma or Beefsteak) have thick walls and less water than other varieties. Instead of buying them at the supermarket, I suggest buying them from a local farmer's market. I picked mine up from an Amish community market - an enormous box full (that I could barely lift) for around ten or twelve dollars. (That being said, I had way more than the 15 lbs this recipe calls for, so I made more than one batch) If possible, buy all of your salsa veggies this way.

The tomatoes used to make salsa should be skinned (peeled) prior to using. Otherwise, the skins will become tough and chewy and not very delicious.

The easiest way to remove the skins from tomatoes is as follows:

Fill your large saucepot with water and bring it to a boil. Then place a few (4 or 5) tomatoes in the water at a time. Start your timer, and leave them in for about 45 seconds. Then, immediately transfer them over to a bowl of ice water. After they've cooled (just a few seconds), the skins will slide right off.

After you've skinned all of your tomatoes, it's time to seed and juice them. To do so, cut your tomato in half, then squeeze each half into a bowl (instead of getting rid of this juice, I canned it too - now I have several quarts of fresh tomato juice on hand!). When you squeeze, a lot of liquid and seeds should come out - don't try and get every drop of liquid out of the flesh, just a squeeze or two is fine. But be careful, as you can never tell where the juice will squirt - I got myself in the eye a few times, not to mention the walls, counters, and cabinets near me!

Once you've squeezed most of the liquid and seeds out, cut up the tomatoes to whatever size chunks or pieces suit your taste (I made a pretty chunky salsa). Empty the water from your saucepot, then throw the chopped tomatoes in there (just don't turn on the heat yet)

Step 4: Prepare Your Peppers and Seasonings

Chop up your onions, jalapeños, and any other peppers you're using to whatever size you want (if you don't like big chunks, you can use a food processor) and add them to the saucepot with the tomatoes.

Before you mince up your garlic, smash the clove with the flat side of your blade. If you're adding fresh cilantro, chop it up now, too.

Add the rest of the ingredients to your saucepot, and mix it all together with a large spoon.

Note: The onions started getting to me, so I used my handy pair of Dora the Explorer swim goggles - they worked perfectly.

Step 5: Simmer Your Salsa

Bring the salsa to a simmer for 30 minutes. This is to get the salsa hot enough to be ready to fill our hot jars.

As it simmers, taste your salsa, and adjust your spices accordingly. If you've gotten it spicier than you'd like, adding more tomato products will help tone it down.

If it's thicker than you'd like, thin it out with the juice we squeezed out earlier. On the other hand, if it's too think, you can either add more tomato paste, or let the water simmer off (which could take a while).

Step 6: Fill Your Jars

Once your salsa is hot, remove your jars from the dishwasher or water bath and place them on a towel. Immediately fill your jars to 1/4 inch headspace (using a headspace tool or measuring tape).

Once your jars are filled, wipe the rims off with a damp towel to remove any drips. This is very important - if you skip this step, your seal may not form properly.

Remove lids, one at a time, from the simmering water, quickly dry off, and place on top of filled jar. Then, screw on the band (hold the lid in place with one finger in the center, and use the other hand to screw on the band).

Step 7: Process Your Salsa

Once the caps (lid+band=cap) are on your jars, place them back in the canner or stockpot filled with boiling water. You can place as many jars as will fit, but don't overcrowd them. Replace the lid of the canner or stockpot, and adjust the heat to medium high. When the water returns to a boiler, start your timer.

Process your salsa for fifteen minutes. When the processing time is over, turn off the heat, remove the lid to the canner or stockpot, and let everything sit for another five minutes. Then, using a jar lifter (or tongs) remove the jars from the canner or stockpot and place them on the towel. Make sure to leave an inch or two of space between the jars to help them cool. Once you've set your jars on the towel, do not move them until after they are cool and you have checked the seals - doing so could prevent the lids from sealing properly.

Note: If the metal bands loosen during processing, it is okay! Do not re-tighten them! Don't mess with the cap at all, just to make sure everything seals properly.

Step 8: Cool Jars and Test Seals

As your jars are cooling, they should start sealing. Each time a lid seals, you will hear a popping sound. You can also tell by looking at the lids whether or not they have sealed.

After at least 12 hours (but before 24 hours) you can can test your seals. Press the center of the lid to make sure it is concave, then remove the band and (gently!) try to lift (not pry) the lid off with your fingertips. If the center doesn't flex up and down, and you can't lift the lid by gently pulling, then your jar has a good vacuum seal.

In the event that some of your jars do not seal properly, you can reprocess them. To do so, remove the band and lid and empty your salsa into a saucepot. Reheat them by bringing them up to a boil, then ladle them into a clean, hot jar as before. Place a new, hot lid on the jar (make sure you wipe the rim off!), hand-tighten the band, and process them again for the full fifteen minutes.

Step 9: Store and Enjoy

After your jars have completely cooled, label and date them.

After you've eaten your salsa, the jars and bands can be reused in future canning projects. However, you should never reuse lids - always purchase new lids (they are inexpensive) to ensure a proper seal.