Heat up olive oil in a heavy bottom saucepan and sauté rice on medium heat. Keep stirring until rice begins to brown, then cover with 2 cups liquid. Bring to a boil, then lower the heat on low and simmer, uncovered, for 12-15 minutes. Leave the rice untouched (do not stir), then remove from heat and let it sit for 5-10 minutes with lid on.
Add lime juice, lime zest, and stir in chopped coriander. Fluff with a fork and season with salt.
For the other ingredients:
Roasted cauliflowers: Preheat the oven to 425˚F (220˚C). Place the cauliflower florets together with the lemon halves onto a baking sheet lined with parchment paper. Season with paprika, salt, pepper, olive oil, and toss to coat. Spread into a single layer and roast for 15 minutes, then juice the halved lemons over the cauliflower, toss, and roast for 10 more minutes, or until desired tenderness and golden at the edges.
Black Beans: Heat the black beans with the spices (chilli and cumin) in a small saucepan until warmed through, adding a little water or oil as necessary. Keep heat on low to keep warm.
Mango salsa: Combine diced mango with red onions, coriander, and lime juice in a bowl. Set aside.
Avocado: Mash with a fork, then season with salt and pepper.
For the jalapeño ranch dressing:
Mix all the ingredients in a blender or food processor until smooth.
Assemble the bowls with one serving of rice, black beans, a few spoonfuls of mashed avocado, mango salsa, and roasted cauliflowers. Drizzle with the spicy jalapeño ranch dressing, and it’s ready.