Make this classic dish with homemade beef stock. In a roasting pan, place 2 lbs of beef marrow bones and trimmings with 2 onions, 4 carrots, 1 leek, and 4 ribs of celery with leaves. Its not necessary to peel the vegetables and they only need to be cut into quarters. Drizzle a little olive oil over everything in the roasting pan and pop into 350° F. oven for 45 minutes until bones and onions have caramelized. Transfer roasted ingredients to a stock pot, add 1 cup of red wine to the hot roasting pan to deglaze, scrape up the drippings, and pour into stock pot. Cover with water, bring to a boil, reduce heat to a simmer and add 2 sprigs of thyme and 8-9 sprigs of parsley. Let simmer on low heat for 6 hours or longer, skimming off any scum that floats on the top. Do not stir the stock while its cooking. Strain the stock through a fine mesh sieve or cheese cloth. Refrigerate over night. Remove solid fat layer. Reserve 1 quart for French onion soup and freeze remaining stock in freezer safe containers.
French Onion Soup