Pat the shrimp very dry with paper towels and place in a small bowl. Drying shrimp removes surface moisture so they sear rather than steam, producing better color and texture.

Add 1 tsp olive oil, 1 tsp lime juice, 1/4 tsp smoked chili powder, a pinch of salt and a few grinds of black pepper to the shrimp and toss to coat evenly. Let rest 5 minutes while you prepare the crema. The oil helps the spice stick and the acid brightens flavor; a short rest lets flavors adhere without cooking the shrimp.

Make the crema: in a small bowl, combine 30 g Mexican crema (or Greek yogurt) with 1/2 tsp lime juice, a pinch of salt and 1–2 turns of black pepper. Stir until smooth. The lime in the crema cuts the richness and ties the sauce to the shrimp.

Warm the tostada: place the corn tostada on a wire rack over a medium oven (or under the broiler for 30–45 seconds) or heat in a dry skillet for 20–30 seconds per side until fragrant. Warming crisps it and evaporates any surface moisture so it stays crunchy under the toppings.

Heat a small nonstick or cast-iron skillet over medium-high heat until hot — about 1–2 minutes. A hot pan gives the shrimp an immediate sear for caramelization; a cool pan would make them rubbery.

Add the marinated shrimp to the dry, hot skillet in a single layer (you should hear a sizzle). Cook 1.5–2 minutes on the first side without moving them so they develop a golden edge, then flip and cook another 30–60 seconds until just opaque and curled. Shrimp cook very quickly; overcooking makes them tough. They should register about 120–135°F (49–57°C) if you use a thermometer.

Remove the shrimp from the pan immediately to stop carryover cooking. If you like a touch more smokiness, sprinkle an additional pinch of smoked chili powder over the hot shrimp — the residual heat will bloom the spice.

Assemble the tostada: spread a thin, even layer (about all of it) of the lime crema over the warmed tostada to create a moisture barrier — this prevents the tostada from becoming soggy and adds creaminess.

Arrange the cooked shrimp on the crema, then top with 2 tbsp pickled red onion, 15 g crumbled cotija, and 1 tbsp chopped cilantro. Add a fresh squeeze of lime if you like. The pickled onion gives acidity and crunch, cotija contributes salty umami, and cilantro adds herbal brightness.

Serve immediately on a small plate. Eat within a few minutes so the tostada stays crisp; if you need to hold it, keep components separately and assemble when ready.