Sprinkle chicken with salt and pepper (I like 1/2 teaspoon salt and 1/4 teaspoon pepper). In a large skillet over medium-high heat, heat oil until shimmering.
Arrange chicken in a single layer and cook until golden brown on one side, about 6 minutes. Flip chicken, add water, and cover.
Continue cooking until the internal temperature reaches 165 degrees at the thickest part of a breast, about 4 to 5 minutes longer. Transfer to a plate and tent with foil.
Add balsamic vinegar and garlic to skillet and stir until fragrant, about 30 seconds. Add tomatoes and bring to boil. Reduce heat and simmer until tomatoes have softened and opened, about 5 to 7 minutes. Stir in basil and season to taste with salt and pepper.
Return chicken to skillet, nestling among tomatoes. Top with mozzarella cheese and cover until cheese is melted, about 30 seconds.
Boneless, skinless chicken breasts: For weeknights, I swear by this quick-cooking chicken cut. Chicken breast tenderloins will save you another minute or two, if you prefer. Boneless chicken thighs also work well; just be sure to cook any of the above to 165 degrees in the thickest part of the meat.
Grape tomatoes: Or cherry tomatoes; any small variety will do. Not only do these roast up quickly and burst in your mouth in the most delightful way, but they are also the best option year-round. Smaller tomatoes contain less water, which means you'll score more concentrated tomato flavor and less seedy, water-logged results.
Fresh basil: Little can compare to the fresh, peppery flavor of basil straight from the herb garden. That said, you can swap in a pinch of dried basil if it's winter and you can't find fresh.
Fresh mozzarella: With a saltier flavor than regular mozzarella and a lusciously creamy texture that truly makes this dish, you'll often find fresh mozzarella sold in a liquid brine with a base of whey or water.
Yield: This Caprese Chicken recipe makes four dinner-sized servings of chicken and saucy tomatoes.
Storage: Store leftovers covered in the refrigerator for up to 4 days.