Preheat the oven to 350?F (175?C) and grease a muffin tin.

In a mixing bowl, combine flour, baking powder, baking soda, and salt.

In another bowl, mix sour cream, milk, egg, vegetable oil, and taco seasoning until smooth.

Gradually add the wet ingredients to the dry ingredients and mix until just combined.

In a skillet, cook the ground beef over medium heat until browned.

Drain excess fat and stir in black beans, corn, and taco seasoning. Cook for another 5 minutes.

Spoon the cupcake batter into the muffin tin, filling each cup halfway.

Add a spoonful of the beef filling on top of the batter, then cover with more batter.

Sprinkle shredded cheese on top of each cupcake.

Bake in the preheated oven for 20-25 minutes or until a toothpick comes out clean.

Let the cupcakes cool slightly before removing from the tin.

Top with shredded lettuce, sour cream, diced tomatoes, and jalape?os before serving.