Prep the shrimp: If the shrimp are whole or shelled with tails, trim to bite-size pieces (roughly 1" chunks). Because these shrimp are already cooked or cured, we’re not looking to cook them further — we’re only letting them pick up bright lime flavor. Cutting to uniform pieces ensures even flavor and an elegant bite.

Combine the aromatics: In a medium bowl, mix the diced tomato, finely diced red onion, chopped jalapeño and cilantro. Add the lime juice, olive oil, kosher salt and black pepper. Mixing the vegetables and acid first allows the lime to macerate the onion and tomato slightly, softening sharp edges and marrying flavors.

Add the shrimp and marinate briefly: Fold in the chopped shrimp and stir gently to coat. Let the mixture rest in the refrigerator for 8–12 minutes. Why brief? With already-cooked shrimp, long exposure to acid (lime) can make the texture tough and rubbery; 8–12 minutes is enough for bright flavor infusion without compromising tenderness.

Prepare the avocado and greens: While the ceviche marinates, toss the mixed greens lightly with a tiny pinch of salt and a drizzle of lime juice (about 1/2 tsp) to wake up their flavor. Dice the avocado and toss it with a few drops of lime (this prevents browning and adds brightness). Doing this just before assembly preserves the avocado's creamy texture and color.

Taste and adjust: After marinating, taste the shrimp mixture and adjust seasoning — add a pinch of sugar or honey if the lime is too sharp, or more salt if flavors are muted. Small adjustments at this stage let you balance acidity, heat and salt before plating.

Assemble the dish: Divide the dressed mixed greens between two chilled plates. Spoon the shrimp ceviche on top, placing the diced avocado gently to one side so it keeps its shape. Finish with a scatter of extra cilantro and a crack of black pepper. Building the plate this way keeps the greens crisp and the avocado from getting mashed.

Serve immediately: Serve the ceviche chilled with lime wedges on the side. Because the avocado will continue to soften and the shrimp will continue to sit in acid, this dish is best eaten within 30–45 minutes of assembly for optimal texture.