Preheat oven to 350°.
Place 1 cup beans in a shallow bowl, and mash with a fork. Place in a medium saucepan; add remaining beans, corn, and next 4 ingredients. Bring to a boil; cover, reduce heat, and simmer 10 minutes. Uncover and cook until thickened and bubbly, stirring occasionally. Set aside, and keep warm.
Place tortillas in a single layer on a baking sheet; bake at 350° for 10 minutes or until crisp.
Spread bean mixture evenly on tortillas. Top with lettuce, chopped tomato, and cheese. Top each with 2 tablespoons yogurt.