Preheat the oven to 200 degrees F.
For the homemade dry rub:
On a parchment paper-lined baking tray, put the garlic, ginger, shallots, and onions and bake in the oven 4 hours, or until dried. Using a food processor, reduce into a powder with the brown sugar, salt, and pepper. Set aside.
Coat the brisket with the spice mixture. Cover and keep in the refrigerator overnight to marinate and flavor the meat.
For the apple barbecue sauce:
In a large bowl, mix together the onion, chipotle pepper, garlic, ketchup, honey, molasses, soy sauce, Worcestershire sauce, lemon juice, salt, and pepper, to taste.
Preheat the oven to 350 degrees F.
Place the brisket, fat-side up, into a heavy baking pan just large enough to hold it, and pour sauce over it. Cover tightly and bake for 4 hours or until fork-tender.
Transfer the brisket to a cutting board and keep warm.
Strain and pour the sauce in a stockpot and let reduce for about 10 minutes on medium high heat until thick. Remove excess fat.
Cut the meat with a sharp knife against grain, to desired thickness.
Garnish onion buns with the meat, sauce, tomatoes, lettuce and top with deep-fried onion rings.
Cook's Notes: You can buy dried onions and garlic from grocery stores instead of preparing it. The apple barbecue sauce is a recipe on its own and very versatile. It can be used as a dip, as a sauce or as a glaze for other meats like chicken, pork, etc.
The brisket can be served on its own and served with mashed potatoes and vegetables.
Brisket can also be sliced and frozen for later use.
Make the brisket the day before and reheat for best flavor.