| Slice onions and spread over bottom of pan. Crush and chop 15 cloves of garlic. Wash brisket and place in large roasting pan on top of onions and garlic. Chop last 15 cloves of garlic and sprinkle over the brisket. Sprinkle salt all over the brisket. Generously grind fresh pepper all over the brisket. Spray foil with vegetable spray. Cover brisket and place in 350 oven. Roast for 4 - 6 hours or until knife inserted in thickest part slides in very easily. It's good to roast this the day before you'll be eating it. Cool it and throw away the congealed fat that rises to the top. Slice the brisket and put back in the gravy to reheat. note: You can add 2 boxes of sliced or whole mushrooms into the gravy right when you take it out of the oven to cool. Put the foil back on top . They will cook slightly as the brisket cools and then again when you reheat the brisket. This way they do not overcook. | 
