Preheat your broiler with oven racks in thirds; place a baking sheet on top rack. Let baking sheet preheat.
Put peppers, onion, and mushrooms in a large bowl. In a small bowl, whisk together avocado oil, garlic, and seasonings until smooth. Pour over veggies and toss well to coat.
Carefully but quickly remove baking pan and scatter veggie mixture over. Place baking sheet back in the oven on top rack and cook for 12-14 minutes, or until veggies are browned and softened, stirring once halfway.
Meanwhile, make the guacamole: in a medium bowl, mash the avocado with a potato masher until the desired texture. Stir in pico de gallo, juice of 1/2 lime, and 1/2 teaspoon salt. Taste and correct seasonings, adding more lime juice or salt as desired.
Meanwhile, make the cilantro-lime cauliflower rice: Stir together all ingredients, starting with the juice of 1/2 lime. Taste and correct seasonings, adding more lime juice, cilantro, or salt as desired.
After 12-14 minutes of cooking, remove pan with veggies from the oven. If desired, sop up juices naturally produced when cooking down the veggies by carefully tilting the pan up at an angle and letting the juices pool in a corner. Carefully, use 1-2 balled up paper towels to soak up juices, then discard.
Serve in tortillas or lettuce cups with guacamole, pico de gallo, and finish with garnishes. Serve with a side of cilantro lime cauliflower rice. Alternately, serve as a burrito bowl by spooning cauliflower rice into serving bowls, topping with veggie mixture, then finishing with guacamole and other garnishes.