Step 1: Season the Shrimp : In a bowl, toss shrimp with olive oil, chili powder, paprika, cumin, garlic powder, salt, pepper, and lime juice.
Step 2: Cook the Shrimp : Heat a skillet over medium-high heat. Cook shrimp for 2–3 minutes per side until pink and opaque. Remove from heat.
Step 3: Make the Avocado Crema : Blend avocado, sour cream, lime juice, garlic, salt, and water until smooth and creamy.
Step 4: Prepare Toppings : Chop lettuce, tomatoes, onion, and cilantro. Set aside.
Step 5: Assemble the Tostadas : Spread avocado crema on each tostada shell. Top with shrimp, lettuce, tomatoes, onion, and cilantro.
Step 6: Serve Immediately : Serve while tostadas are crisp and fresh.