Remove the corned beef from the package, rinse off the brine, and pat it dry. Discard any excess brine.

Crush the spices that come with the corned beef using a mortar and pestle or a heavy pan.

In a bowl, mix the crushed spices with minced garlic, brown sugar, black pepper, and fennel seeds.

Rub Dijon mustard on the top fatty side of the corned beef.

Spread the combined seasonings on top of the mustard.

For the oven method: Preheat the oven to 325 degrees F. Pour apple juice or apple cider and apple cider vinegar into a roasting pan. Place the corned beef in the pan, seasoned side up, and cover it. Cook for about 50 minutes per pound or until the internal temperature reaches 145 degrees F.

For the slow cooker method: Pour apple juice or apple cider and apple cider vinegar into the slow cooker. Add the corned beef, seasoned side up, and cook on low for 6 to 8 hours or until the meat is tender.

Just before serving, place the corned beef on a foil-lined sheet pan and broil it 6-7 inches away from the heat for 5-6 minutes to caramelize and crisp the top.