Preheat the oven to 400 degrees F and set out a 3-quart round baking dish.
In a skillet over medium-high heat, add 2 tbsp of avocado oil. Add the diced onion, minced garlic, diced bell pepper toppings, and the diced sweet potato. Add all the seasoning and sauté for 5 minutes. Add 4 tbsp of the chipotle pepper adobo seasoning and sauté for an additional 5 minutes.
Remove the skillet from the heat and transfer the mixture to a large mixing bowl. To the bowl, add the remaining ingredients: black beans, cooked quinoa, and lime juice, and mix to combine. Taste and adjust seasoning as needed (adding more salt, pepper, or more spices as desired).
Fill/Stuff the bell peppers with about 1/2-3/4 cup of the mixture.
To the round baking dish, add chopped tomatoes and any leftover filling. Add 2 tbsp of avocado oil and toss everything together. Carefully transfer the stuffed bell peppers to the baking dish and cover it with the lid or foil.
Bake for 30 minutes covered. Remove the lid/foil and bake for an additional 20 - 25 minutes, or until the bell peppers are soft and slightly golden brown.