Season chicken breasts with olive oil, salt, pepper, garlic powder, onion powder, smoked paprika, and oregano.
Massage spices into chicken and refrigerate for 1 hour or overnight.
Zest and juice lemons; whisk dressing ingredients until creamy.
Prepare vegetables for grilling and salad; keep lettuce chilled.
Preheat and oil grill grates.
Grill chicken until cooked through and well marked; rest before slicing.
Grill radishes and bell pepper until lightly charred.
Assemble salad with romaine, vegetables, grilled veggies, cheese, and chili.
Slice chicken and place on top.
Drizzle lemon dressing and garnish with cilantro.