Grilled Chicken Salad with Rustic Guacamole, Romaine and Queso Añejo - Rick Bayless

Ingredients

• 1/2 cup vegetable or olive oil, plus a little more for the onion
• 4 cloves garlic
• 2 serrano chiles , stemmed and halved (or 1 large jalapeño)
• 1/2 cup fresh lime juice
• 3/4 cup (loosely packed) roughly chopped cilantro
• 1/4 teaspoon ground black pepper
• salt
• 4 boneless, skinless chicken breast halves (about 1 1/4 pounds total)
• 1 medium white onion, cut into 1/2-inch slices
• 2 ripe avocados
• 2 medium romaine hearts, sliced crosswise into 1/2-inch-wide ribbons (about 8 cups)
• 1/3 cup grated Mexican queso añejo or other garnishing cheese such as Romano or Parmesan