Place the 1/4 cup olive oil, 2 cloves finely minced garlic, zest from 1 lemon, juice from 1 lemon, zest from 1 orange, juice from 1 orange, 1/2 teaspoon dried basil, 1/2 teaspoon dried oregano, and 1/4 teaspoon dried thyme in a resealable bag. Seal and shake to mix.: The moment you combine these ingredients you should notice a burst of citrus aroma, and that oil will visually coat the mixture, creating a glossy marinade. The sensory cue to look for is uniform suspension of herbs and citrus bits in the oil, not separated pools. This mixture matters because the oil helps carry volatile flavors while the acid from the juices begins gentle tenderization of the chicken . One thing to avoid is over zesting in a coarse way, which can leave fibrous pieces that do not blend smoothly; use a fine grater for fragrant, even distribution. If the bag is not sealed well you risk spills and uneven coating, so check the seal before shaking.
Place the 2 boneless skinless chicken breasts cut in half in the bag, seal, and shake until the chicken is coated with the marinade.: As you add the chicken to the bag, press the air out and move the pieces so they nestle in the marinade, ensuring full contact. When you shake, you should hear the soft slosh of liquid and see the pieces turn glossy, which means they are coated. This technique matters because even coating allows the citrus and herbs to flavor the surface evenly and prevents dry spots during grilling. A typical mistake is overcrowding the bag, which limits movement and leads to patchy seasoning; if you have large breasts, do them in batches. Also, avoid stabbing the meat with a fork to mix, because that releases juices and dries the chicken .
Refrigerate and marinate for at least 30 minutes or up to 2 hours. Preheat the grill or a grill pan over medium-high heat.: During this resting period the acid will lightly penetrate the outer layer of the chicken , and the aromatics will meld, creating a complex surface flavor. You will notice the marinade slightly thickens as the herbs hydrate. Preheat your grill until it feels hot to the touch and is producing a steady sizzle when you test a drop of water, which indicates it is in the correct medium-high range. This step is key for even searing and those coveted grill marks. Over-marinating beyond two hours can begin to firm the proteins because of the acid, so keep within the recommended window.
Remove the chicken from the marinade and season both sides generously with salt and pepper to taste. Grill for 4-5 minutes on each side or until chicken is cooked through.: As you place the pieces on the hot grill you should hear an immediate sizzle and smell a burst of citrus and garlic hitting the heat, which is a reassuring cue. Let the chicken sit without moving for a few minutes to develop caramelization and grill marks, then flip once to preserve juiciness. The visual cue for doneness is a golden to light brown exterior with clear juices running and an internal temperature reaching about 165 degrees Fahrenheit. One common mistake is flipping too frequently, which prevents good caramelization and can dry the meat out, so resist the urge to prod. Also, avoid putting wet marinated pieces directly onto the grill as excess liquid can cause flare ups, pat lightly if necessary.
Remove from the grill and let the chicken rest for 5 minutes. Sprinkle with 2 tablespoons chopped parsley and serve with lemon wedges for serving if desired.: The resting phase is when juices redistribute back into the meat, which you can sense by touch the chicken will feel slightly springy rather than tight. During these minutes the aroma will mellow and the surface will set, making for cleaner slices that retain moisture. Garnishing with fresh parsley adds a green pop and bright herbaceousness, while the lemon wedges let diners add finishing acidity to taste. A frequent misstep is slicing immediately after grilling, which lets the juices escape and results in drier meat, so always wait a short rest before serving.