Heat oil in skillet over medium heat. Cook onion 3 to 5 minutes, or until soft. Add garlic, and cook 1 minute, or until translucent and fragrant.
Stir in beans, chili powder and 1 cup water.
Reduce heat to medium low, and simmer 10 minutes, or until most of liquid has evaporated.
Remove from heat. Mash beans until mixture is thickened but still chunky, and some beans remain whole.
Stir in 1 cup salsa and corn, and season with salt and pepper. Cool.
Preheat oven to 425F. Coat 2 large baking sheets with cooking spray. Spoon 1/3 cup black bean mixture down center of tortilla.
Roll tortilla around filling, and secure closed with toothpick. Set on prepared baking sheet. Repeat with remaining tortillas and black bean mixture.
Bake 6 to 10 minutes, or until tortillas are browned and crisp. Note: If you want to add more crispiness, you can put the flautas under the broiler for a few min and top each one with 1Tbsp of cheese to get a nice crust on top. Meanwhile, combine cilantro and remaining salsa in small bowl. Place 2 flautas on each plate, and top with remaining salsa.