Simple "Minced" Ceviche for Tostadas - Rick Bayless

Ingredients

• 1 pound sashimi-quality skinless meaty ocean fish filet (many fish work well here, but halibut or bass are always reliable)
• 1/3-1/2 cup fresh lime juice
• 1 medium-large red-ripe tomato seeded and finely chopped
• 1 small carrot, peeled and shredded
• Fresh hot green chiles to taste (usually 1 to 2 serrano or 1 jalapeno chiles), stemmed, seeded and finely chopped
• 1/4 cup (loosely packed) chopped fresh cilantro plus leaves for garnish if you wish
• Salt
• 10-12 5-inch tostadas
• 1 avocado for garnish (optional)