Thaw rolls at room temperature until soft but still cold, about 10 minutes.

Spray cookie sheet with cooking spray.

Cut each roll into quarters; shape dough pieces into balls.

Place on cookie sheet.

Brush tops of dough balls with butter.

Cover with plastic wrap sprayed with cooking spray.

Let rise in warm place 2 hours to 2 hours 30 minutes until doubled in size.

Heat oven to 350°F.

Remove plastic wrap.

Bake buns 12 to 15 minutes or until golden brown.

Remove from pan to cooling rack.

Meanwhile, in medium bowl, mix salsa ingredients.

Cover; refrigerate until serving time.

In 10-inch nonstick skillet, heat 1 teaspoon of the oil over medium heat.

Add onion; cook 3 to 4 minutes, stirring often, until softened.

Remove from heat; cool slightly.

In medium bowl, mash beans with potato masher or fork, leaving a few beans whole.

Stir in egg, bread crumbs, garlic, cumin, salt and pepper.

Add cooled onion; mix until thoroughly combined.

Shape mixture into 20 (1-inch) balls, using about 1 scant tablespoon per ball.

In same skillet, heat 2 teaspoons oil over medium heat.

Place half of the bean balls in skillet; with back of spatula, flatten balls into patties, about 11⁄2 inches in diameter.

Cook 4 to 6 minutes, turning once, until browned.

Remove from skillet; cover to keep warm.

Repeat with remaining 2 teaspoons oil and bean balls.

Split buns in half.

On bottom half of each bun, place lettuce piece, bean patty, cheese quarter and 1 heaping tablespoon corn salsa.

Cover with top halves of buns.