In a small bowl, mix together oregano, cumin, garlic powder, and salt.

Reserve 1 cup of salsa for the topping.

Trim the chicken breasts.

Sprinkle the seasoning over both sides of the chicken breast.

Spoon part of the 2 cups of salsa on the bottom of the slow cooker.

Place the chicken breast on top.

Pour the remaining salsa over the top of the chicken.

Cover and cook on low for 4 hours or until the internal temperature of the chicken reaches 165 degrees.

Use forks to shred the chicken.

Add the corn and black beans and continue cooking for 15-20 minutes until heated through.

Prepare your toppings.

Place rice in the bowl, top with the chicken mixture.

Add the toppings of your choice and serve.