Pound chicken to even thickness. Mix spices and coat both sides of each breast firmly.
Cook chicken in olive oil over medium-high heat, 5 to 6 minutes per side undisturbed, until 165°F internal. Rest 5 minutes then slice across the grain.
Char corn in the same dry skillet over high heat for 3 minutes, stirring once, until lightly blackened.
Whisk all dressing ingredients together until smooth. Thin with water to a drizzleable consistency.
Build each bowl with romaine, then beans, corn, tomatoes, onion, and avocado. Top with sliced chicken, drizzle dressing over everything, and finish with cilantro.