At least 1 hour before grilling, soak wood chips in enough water to cover. Cover both sides of brisket (do not trim fat) with the Mustard Rub. Evenly sprinkle the Brisket Rub over Mustard Rub. Cover and chill for 20 minutes or up to 4 hours.
Drain wood chips. For a charcoal grill, arrange medium-low coals around a drip pan. Test for low heat above the pan. Place about half of the drained wood chips over the coals. Place brisket, fat side up, on grill rack over drip pan. Cover and grill for 1-1/2 hours without removing the lid.
After 1-1/2 hours, use a spritzer-bottle to lightly spray the brisket with apple juice. Add the remaining half of the wood chips while lid is off. If necessary, add additional charcoal to maintain medium-low coals. Cover and grill 1-1/2 hours more, spraying brisket with apple juice 2 to 3 times and adding additional coals as needed to maintain medium-low coals. (For a gas grill, preheat grill. Reduce heat to low. Adjust for indirect cooking. Add wood chips according to manufacturers directions. Grill as above, except place meat, fat side up, on a rack in a roasting pan.)
Remove brisket from grill. Place in a foil-lined 13x9x2-inch baking pan. Bake, covered, in a 275° oven for 1 hour or till the meat is very tender and internal temperature registers 190 degrees F to 195 degrees F. Remove from oven. Let stand, covered, for 20 minutes before carving.
To serve, thinly slice meat across the grain. If you like, serve with barbecue sauce. Makes 12 to 14 servings.
In a small bowl stir together Dijon-style mustard, Worcestershire sauce, soy sauce, and red wine vinegar. Use immediately or cover and chill in the refrigerator up to 2 weeks.
In a small bowl stir together sugar, salt, MSG (optional), chili powder, paprika, lemon-pepper seasoning, onion powder, garlic powder, black pepper, and cayenne pepper. Store in a covered container at room temperature.