TUNA CEVICHE WITH AVOCADO

Ingredients

• 1/2 cup fresh lemon or lime juice
• 1/4 cup extra virgin olive oil
• 1 clove garlic, peeled and roughly chopped
• 1 teaspoon kosher salt, plus more to taste
• 1 teaspoon merquén
• 1/2 serrano or jalapeño pepper, seeded and roughly chopped
• 1 pound sashimi-grade tuna, chilled, cut into 1/2-inch cubes
• 1 ripe but firm avocado, pitted, peeled, and cut into 1/2-inch cubes
• 1/2 red or yellow bell pepper, seeded and diced
• 1/4 medium red onion, very thinly sliced
• 2 tablespoons chopped fresh cilantro leaves
• Leaf lettuce or radicchio leaves for serving