Pat the shrimp completely dry, then place in a glass bowl with cumin, smoked paprika, minced garlic, juice of one lime, one tablespoon oil, sea salt, and black pepper. Stir until evenly coated. Cover and refrigerate for fifteen minutes if you have the time; even a short rest lets the flavors penetrate.

Set a large heavy pan over medium heat for about two minutes so it reaches an even temperature. Pour in the remaining tablespoon of oil and tilt the pan until the surface glistens.

Arrange the shrimp in a single layer. Cook ninety seconds on the first side, then flip and cook another sixty to ninety seconds. Remove as soon as the shrimp turn opaque pink and form a loose C shape; this prevents a tough, rubbery texture.

Transfer the hot shrimp to a clean mixing bowl. Add diced avocado, chopped cilantro, thin chili slices, and juice of the second lime. Gently toss to coat, tasting for salt and pepper adjustments.

Lay romaine or butter-lettuce leaves on a serving platter. Spoon a generous portion of the shrimp mixture into each leaf, letting the vibrant juices drip over the lettuce for extra flavor.

Offer extra lime wedges and any optional toppers such as cotija or toasted cashews. Enjoy the cups while the shrimp are warm and the lettuce is crisp for the best texture contrast.