A whole brisket (which includes both the flat and the point) can range from 12 to 16 pounds. We recommend using one no larger than 12 pounds to ensure it will fit in a roasting pan. To peel pearl onions: Bring a pot of water to a boil. Fill a bowl with ice water. Cut off the root end of the pearl onions. Add the onions to the boiling water and cook for 1 minute. Drain, add to the ice water and stir. Pinch the stem end of each onion to remove the peel.