Preheat an outdoor grill for medium-high heat and lightly oil the grate.
Sprinkle chicken breast with salt and pepper. Brush corn and asparagus with 1 tablespoon olive oil.
Place chicken and corn on the grill; close the lid. Grill, turning chicken once and corn as needed, until chicken is no longer pink and corn is charred, 10 to 15 minutes. Remove to a cutting board. Add asparagus and grill, turning often, for 6 minutes.
Slice chicken diagonally. Cut corn from cobs; cut asparagus into 1-inch pieces.
Whisk vinegar, garlic, mustard, paprika, and remaining olive oil together. Season dressing with salt and pepper.
Toss chicken, corn, asparagus, tomatoes, lettuce, and green onion together in a large bowl with the dressing.