6 Lemons (plump as you can get them)
1/2 pound raw shrimp
1/4 pound cooked crab meat
1 ripe tomato
1 medium sized shallot
2 cloves of garlic
1/4 cup chopped cilantro
1/3 cup shelled pumpkin seeds
Olive Oil (optional)
Step 1: Making the Lemon Cups/Juicing the Lemons
Over a bowl and using a grapefruit spoon, small knife or just a regular teaspoon, cut into the pith just outside of the lemon flesh. Make a small shallow cut at first, then slowly cut deeper all around the inside until all or most of the flesh can be removed.
This may take a little practice. All lemons are different and some have a very thin pith that makes this process difficult. You may have to scrape the insides out to get any of the remaining bits. Don't worry though, as long as you get most of the insides out while not piercing the lemon anywhere, you're good to go.
When you've made your cups place them on a sheet pan or large plate and put them in the freezer until they are ready to be filled. (Ceviche is a dish that is best served cold. Freezing the lemon cups helps this greatly and it also gives some structural integrity to them)
Juice the lemon flesh as best you can. This can be done any way you see fit (by hand/citrus juicer, even in a blender or food processor) just make sure to filter out any seeds or fibrous material leaving you nothing but pure lemon juice. When all is done you should have about 1/2 cup of juice. Place in the refrigerator to chill.