Mix the masa harina with the salt and oil; little by little add the water. If you need more, just add it in subtle quantities. The idea is to achieve the consistency of a soft dough.
Heat a pan or skillet on high heat. To cook the sopes, the skillet or pan has to be on medium-high heat.
While heating the pan or skillet, form a ball with the masa harina dough and put it between two pieces of plastic. With a plate that has a flat bottom, apply pressure until you have a flat and even disk or a thick tortilla.
Put each masa disk on the pan until it looks dry on top. Turn it over and leave it until cooked. As soon as you pull it out of the griddle pinch the edges with your fingers. Be careful not to burn yourself, it will be very hot.
Repeat until done. When the sopes are ready, add a tablespoon or two of the refried beans, then some lettuce, Mexican salsa, and a dollop of cream.
You can also add red onion or pickled onion and some sliced chiles.