Line a rimmed, baking sheet with nonstick foil, parchment paper, or a silicone baking mat.
Rinse fish; pat dry with paper towel. Place fish on prepared baking sheet, drizzle with 1 tablespoon olive oil and sprinkle with chili powder and kosher salt. Turn pieces to evenly coat. Bake for 10-12 minutes or until fish flakes easily with a fork.
Meanwhile, in a large, nonstick skillet, heat the remaining 2 tablespoons oil over medium-high heat. Add onions, garlic, and pepper and sauté for 3 minutes, or until softened.
Stir in coconut milk, reduce heat to medium-low and cook, stirring occasionally, for 4-6 minutes or until slightly reduced.
Stir in lime juice and vanilla extract. Season with kosher salt, to taste. Remove from heat.
Plate fish, spoon sauce over fish, and sprinkle with cilantro and nuts, to serve.
Recipe by Go Dairy Free at https://www.godairyfree.org/recipes/tilapia-kickin-poblano-coconut-sauce