Shrimp and Crab Ceviche on Fried Tortillas (Tostadas de Ceviche de Camarón y Jaiba)

Ingredients

• Canola oil
• 18 4"-5" corn tortillas (cut 6" tortillas with a round cutter, if necessary)
• 1 1⁄2 lb. cooked medium shrimp, peeled, deveined, and chopped
• 3⁄4 lb. lump crabmeat
• 1⁄4 cup fresh lemon juice
• 2 Tbsp. chopped cilantro
• 1 large cucumber, peeled, seeded, and chopped
• 2 large tomatoes, chopped
• 1-2 jalapeño chiles, stemmed, seeded, and finely chopped
• 1 small red onion, finely chopped
• Salt
• 2 avocados, peeled, seeded, and cut into slices
• 2 limes, cut into wedges