This recipe is a bit if a mashup between other recipes I have found online with a smidge or so of Alton Brown's version thrown in.
I've made marmalade twice now, and I'll say up front, this is not for the first time jam maker - most recipes say you don't *need* sure-jell or another pectin source for marmalade, but I've needed it both times, and didn't use it the first time. Also, don't use limes. I tried limes in my first batch, and the rinds turn a very unappealing (no pun intended!) color when cooked.
6 oranges - I used organic navel
2 meyer lemons
5 cups orange juice
5 cups sugar
1 box/package pectin powder
triple-sec, around 1/4 cup total
Large slow-cooker - I don't know the quart size, but mine is oval and bigger than average. I can't say whether this would work in a 'normal' round crockpot.
Mandolin slicer with medium-thick blade cutter
Good sized sharp, non-serrated knife
Canning jars, lids and rings: 6-8 pints worth
large, deep pot that will allow water to cover your jars by one inch
Canning tongs, funnel
Wooden spoon for stirring
Cold plate for testing
Ladle, preferably non-metal
Paper towels or clean kitchen towels
Small bowl or pan to hold lids
Step 1: The Fruit!
Setting up your mandolin, USE THE HAND GUARD. Depending on your particular finger-death slicer, set it up to make a little less than a 1/4 inch thick slices of fruit. Cut off the crappy end of your navel orange - you know, the end that is the most full of those bits of inedible pieces - to make a flat surface. Cut until you have a decent fruit/pith ratio, as much as half an inch off the bottom, discard. I have been told that one can use a food processor instead.
Place each orange in your slicer and go nuts - you will probably have to slide some slices out of the way to finish. stack the slices and quarter them, then roughly chop, cutting in each direction two or three times, not a lot, and not enough to reduce the length of the peel pieces too much. Slide the chopped orange and remaining juice on the board into the crockpot using the flat of your knife.. Repeat with the rest of the oranges and lemons, and check the tangerine pieces for seeds. You will probably have to let the juice drip off the board into the crockpot between every orange.
Step 2: Cooking the Marmalade
Add your sugar and orange juice now, stir and walk away for four hours.
After 4 hours of high heat cooking, turn down and cook on low, lid off, for another 2 hours
Check on your marmalade after a total cook time of six hours, and see if your fruit looks cooked down yet or not. Mine was not done until 10 hours total cook time. For the rest of the cook time, leave uncovered on high or medium heat.
When it looks like Marmalade, take a cold plate and drop a teaspoon of your concoction and let it rest for 2 minutes. Tilt the plate. If it slides, it's not done.
Clean the plate and put it back in the freezer for testing in another half hour or hour. At 9 hours into my cook time, I added an envelope of Sure-Jell, because it was just not setting up on its own, even though it had cooked down by almost an inch.
I would say not to let it go more than 9-10 hours.
Test for sugar content periodically near the end of cooking- I like a less sweet marmalade, but you may want more sugar. Test the cooled marmalade on the plate, not when hot out of the cooker.
Step 3: Canning!
Half an hour before you begin canning, bring your pot of water up to a FULL BOIL with the empty jars you are going to use, along with the RINGS ONLY. Do not put the lids in there. Toss in your funnel, tongs and ladle, assuming your ladle will not melt. I have had no problem with extra jars sticking out of the top layer of water during this stage, since they're still up to full boiling temperature and steamed. Boil 1-2 more jars than you THINK you will need.
After fifteen minutes at a full boil, pull the water off the burner (Do not dump it), and use another pair of clean tongs to fish out your jars, rings and other implements.
Arrange the jars on a few layers of paper towels or a clean kitchen towel, place the funnel in the first jar.
Scoop up some of the hot water into another pan or bowl and put the lids in to rest.
Put the sanitized rings in another safe place.
Use your ladle to fill each jar up to within a 1/4 inch to the top of the rim. Wipe rims clean. If using Triple-Sec, add just a splash to each jar-no more than a tablespoon each, then lid and screw on the lids just to closure, but don't tighten them. I've heard that Gran Marnier works great too.
Put your water bath back on the burner, and remove a few inches of water with a measuring cup and discard.
Add as many jars as will fit comfortably in the pot and make sure they're covered by an inch or more of water and not crowded in. Boil at full heat for 10-15 minutes. I had to do two batches. After cooling, you may store in the pantry until opened. This recipe made 6 pints for me.
After removing your last jar from the bath, toss your spoons, ladle, funnel and anything else covered in fruit back into the hot water - it will help your cleaning stage a lot.