MARINADE: Combine 3/4 cup vegetable oil, 1/4 cup + 2 tablespoons soy sauce, 3 tablespoons Worcestershire sauce, 1/4 cup red wine vinegar, about 3-4 tablespoons lemon juice, 1 teaspoon lemon zest, 1/2 tablespoon black pepper, 2 teaspoons minced parsley, 3 tablespoons yellow mustard, 1-2 teaspoons minced garlic (for a more intense flavor use 2), and 1 tablespoon honey in a large bowl.
RESERVE: Set aside 1/3 cup of the marinade and save it for later.
PREP CHICKEN: Remove fat from the chicken and pound the chicken to an even width (about 1 inch wide everywhere.) If breasts are very wide, cut them in half to get them 1 inch wide. Prepping the chicken like this will ensure even grilling and make sure more chicken gets all those great marinade flavors.
MARINATE: Place the chicken in the marinade and marinate for at least 30 minutes to 6 hours. The chicken is best at 4-6 hours. Too much longer and it tends to get salty/cooked by the vinegar and lemon.
PREP GRILL: Make sure your grill grates are clean and greased. To grease, dredge a paper towel in vegetable oil and holding it with tongs rub it all over the grate. Grease once the grill is fully preheated. Preheat the grill to medium heat about 375-450 degrees F. Don't go hotter than 450 to avoid drying out the chicken.
GRILL: Grill the chicken until completely cooked through (about 4-6 minutes per side depending on heat of the grill and thickness) Chicken should be at 160 degrees F at its thickest part (carry over heat will bring it to 165 degrees). For 1 inch thick breasts grilled at 400 degrees, it takes generally 5 minutes on the first side and 4 minutes on the other side.
BASTE: Generously brush chicken with the reserved marinade mix as it grills. Keep grill closed as much as possible though.
OPTIONAL: For a quick lemon butter sauce to serve over the chicken, combine: 3 tablespoons melted butter, 3 tablespoons lemon juice, 1-2 teaspoons lemon zest, 3 tablespoons olive oil, and 3 tablespoons honey in a small bowl. Add some pepper and parsley if desired. Serve with the chicken.