Heat a large pan on medium heat. Once hot, add 1 tablespoon olive oil, garlic, yellow onion, and red onion. Saute until translucent.
Add the cauliflower rice, sea salt, and black pepper. Saute together. Steam for 1 minute, (you are not looking to completely cook the riced cauliflower since will continue cooking in the oven). Remove from heat and transfer to a large bowl.
Add the beans to the bowl and mix to thoroughly combine. Add the sea salt, black pepper, chili powder, cilantro, and lime juice to taste. Set aside.
In a separate bowl, prepare the salsa by dicing the tomato and adding it to the leftover 1/2 red onion. Add cilantro, sea salt, and lime juice to taste. Add to the cauliflower mixture and mix to evenly combine ingredients.
Cut the peppers into halves, remove the seeds, and brush the outsides with olive oil. Place into a baking pan.
Generously stuff the halved peppers with the cauliflower mixture. Cover the baking pan with oven safe aluminium foil.
Bake for 30 minutes covered, then remove the foil. Increase temperature to 400°F and bake for another 15-20 minutes or until peppers are the desired texture and slightly golden brown.