Preheat the oven to 350°F. Line a baking tray with parchment paper or foil.
In a small bowl mix together garlic powder, onion powder, cumin, paprika, oregano, pepper, and salt.
Heat oil in a frying pan over medium-high heat. Add the beans, corn, and taco spice mix and cook, stirring for 2 minutes. This will bring out the flavours in the spices.
Cut the tops off of the mini peppers and remove any core and seeds. Place cut side up on the lined baking tray.
Top with black bean and corn mixture. Then salsa and the remaining ingredients ending with the cheese.
Bake in preheated oven for 10 minutes. Remove tray from oven and place oven rack in top position. Turn broiler on high. Return tray to oven and broil for 2 minutes or until cheese is bubbling and starting to brown. Remove from oven and top with sliced green onions and cilantro leaves if using.
Serve immediately with sour cream and guacamole.