Whisk the olive oil, vinegar, soy sauce, Worcestershire sauce, lemon juice, brown sugar, rosemary, mustard, salt, pepper, and garlic powder in a large bowl until blended. The marinade should look glossy and slightly thickened, like a well-mixed vinaigrette.

Pour ½ cup of the marinade into a separate container before adding any chicken. Keep that reserved portion separate if you want to baste during cooking or simmer it into a sauce later.

Place the chicken in a large resealable bag and pour in the marinade. Press out extra air, seal the bag, and massage the chicken so every piece is evenly coated.

Refrigerate the chicken for at least 30 minutes and no more than 24 hours. For the best flavor and texture, aim for 4 to 6 hours, and poke the chicken with a fork first if you need the marinade to work faster.

Heat the grill to medium-high and oil the grates lightly. When the chicken hits the grill, you want a sharp sizzle instead of a faint hiss.

Lift the chicken from the bag and let the excess marinade drip off before placing it on the grill. Less dripping helps limit flare-ups and keeps the outside from scorching too early.

Cook for 5 to 6 minutes per side, turning once. The surface should pick up charred spots and the meat should feel firmer as it cooks through.

Baste occasionally with the reserved marinade during cooking. Brush lightly so the coating builds flavor without flooding the grates.

Remove the chicken when it reaches 165°F and tent it loosely with foil for at least 5 minutes. That short rest helps the juices settle back into the meat instead of running onto the cutting board.

Heat the oven to 400°F and arrange the marinated chicken on a baking sheet. Leave a little space between pieces so the heat can circulate and brown the edges.

Bake for 18 to 22 minutes, depending on thickness. The chicken is ready when the center reaches 165°F and the juices run clear when pierced.

Rest the chicken briefly before slicing or serving. The texture will stay noticeably juicier if you give it a few minutes before cutting.

Set a large skillet over medium-high heat and add the chicken in a single layer. The pan should sound lively when the chicken goes in, but it should not smoke aggressively.

Cook for 5 to 7 minutes per side, adjusting as needed for thickness. The outside should turn deep golden brown while the center finishes cooking through.

Do not overcrowd the pan, and cook in batches if needed. Giving the pieces space helps them sear instead of steam.

Take the chicken out of the skillet when it reaches 165°F, then let it rest before serving. You’ll keep more juice in the meat and get cleaner slices.