Heat oil and garlic in a small saucepan over medium-low heat until fragrant and starting to bubble, 3 to 5 minutes. Let cool completely. Strain oil through a fine mesh strainer into an airtight container, and discard the solids.

If you buy unwashed quinoa, rinse it under cool running tap water in as fine mesh sieve. Then spread it out on a clean dish towel to dry for 15 minutes. Once the quinoa is washed and dried, or if you have prewashed quinoa proceed with toasting the grain.

Toast quinoa in a medium saucepan over medium-high heat, stirring frequently, until quinoa is very fragrant and makes continuous popping sounds, 5 to 7 minutes. Stir in water and ½ teaspoon salt, and bring to a simmer. Cover, reduce heat to low, and simmer until quinoa is tender and liquid is absorbed, 18 to 22 minutes, stirring once halfway through cooking.

Remove quinoa from heat and let sit, covered, for 10 minutes. Fluff quinoa with a fork, then stir in lime zest, 1 tablespoon lime juice, and ¼ cup cilantro. Season with salt and pepper to taste; cover to keep warm, and set aside.

Pat shrimp dry with paper towels, then toss with chile powder, pepper, and ½ teaspoon salt in a bowl. Heat 1 tablespoon garlic oil in 12-inch nonstick skillet over medium-high heat until just smoking. Add half of the shrimp in a single layer and cook, without stirring, until spotty brown and edges turn pink on bottom side, about 1 minute. Flip shrimp and continue to cook until all but the center is opaque, about 30 seconds. Transfer shrimp to a large plate. Repeat with remaining 1 tablespoon garlic oil and remaining shrimp; transfer to plate, and set aside.

Return now empty skillet to medium high heat. Add tomatoes. Remaining 1 tablespoon lime juice, remaining ⅛ teaspoon salt, and remaining cilantro. Cook until tomatoes are just softened, about 1 minute. Stir in shrimp and cook until shrimp are opaque throughout, about 1 minute. Season with salt and pepper to taste. Transfer shrimp and tomatoes to individual plates and top with avocado. Serve with cilantro lime quinoa and lime wedges.