In colander, drain 1/2 cup of the salsa. Seed and finely chop half of the jalapeno; thinly slice remaining half. In large bowl mash beans with vegetable masher or fork. Stir in muffin mix, drained salsa, 2-1/2 teaspoons chili powder, and chopped jalapeno.
In 12-inch skillet heat 1 tablespoon oil over medium-high heat. Add four 1/2-cup mounds of bean mixture to skillet. Flatten mounds with spatula to 3-1/2-inch-round cakes. Cook for 3 minutes on each side until browned. Remove from skillet. Repeat with remaining oil and bean mixture.
In bowl combine sour cream and 1/2 teaspoon chili powder. Top cakes with remaining salsa, sliced jalapeno, and seasoned sour cream. Makes 4 (2-cake) servings.