If using masa harina, mix it with the water, cover and let stand for 1/2 hour. Mix the lard, salt, flour and baking powder with the fresh or reconstituted masa, kneading it until all ingredients are thoroughly incorporated. If necessary, add a little water to correct the consistency of the dough (the dough should be slightly sticky and form a ball when pressed together. To test, flatten a small ball of dough between your palms. If the edges crack, add water to the dough, a tablespoon at a time, until a test piece does not crack). Divide into 12 pieces, place them on a plate and cover with plastic wrap. Set a griddle or heavy skillet over mediumlow heat. Place a 7 inch square of heavy plastic (like that used for freezer bags) on the counter and flatten a piece of masa onto it. Pat and press the dough into a 4 inch diameter circle about 1/8 inch thick. With the sambuta still attached to the plastic, flip it over onto one hand, dough side down, then carefully peel off the plastic.

Lay the sambuta on the heated griddle and bake, turning over every minute or so, until it is lightly browned and crusty, about 3 or 4 minutes. Cool on a wire rack, then form and bake the remaining 11 sambutas in the same way. Heat 3 inches of vegetable oil to 375 degrees in a large heavy saucepan or deepfat fryer. Fry the sambutas a few at a time for about 1 1/2 minutes, turning over frequently. The 2 sides should have puffed apart by about 3/4 inch. If they don=t puff, you can just split them apart with a knife when serving. Drain on paper towels. When ready to serve, use a small pointed knife to cut an opening in the pocket. Stuff a little of the bass escabeche inside and finish with some of the shredded lettuce.