We eat a lot of Mexican food here in Southern California, and masa is a staple in my house.
Sopes are kind of like tostadas, but the tortilla part is a lot thicker and softer, like a flat cornbread. Once I ate at a place that called the thick tortillas "huaraches" which means sandals, but hopefully you will like these a whole lot better.
To make "huaraches":
Combine 2 cups masa, 1/4 tsp. salt, and 1 1/4 cups water. Mix thoroughly for about 2 minutes to form a soft dough.
Divide masa into 20 portions and roll into balls. Cover with plastic wrap to prevent drying.
Preheat ungreased griddle to high temperature. Place a ball between two sheets of heavy-duty plastic wrap. Roll out or flatten ball to form a 3" diameter circle (if you have a tortilla press your life will be much easier) and about 1/2 " thick. The thickness is more important than the diameter.
Cook sope for one minute on the preheated griddle. Turn and cook the second side until lightly browned.
Heat 3/4" oil in a frying pan and fry sopes until lightly golden and drain on paper towels (I skipped the frying step to keep it healthy but if you can spare the calories, they'll definitely be more delicious).
Top sopes with anything you want: keep them traditional with refried beans, cooked chicken, chopped tomatoes, onion, cheese (if you live in an area that sells queso fresco, I highly recommend it), lettuce, and sour cream. Or go a little wacky and use soy chorizo cooked with onion and potato, and cheddar cheese--this also makes a great breakfast.