Sanitize all work areas, cutting boards, equipment and sinks used in the preparation of this recipe.
Wrap thyme, bay leaves, peppercorns and rosemary in cheese cloth. Tie with butchers twine. Set aside.
Confirm weight of trimmed and peeled onion. Julienne onion ΒΌ" thick, with the grain.
Melt butter with evoo in a heavy bottom pot or rondeau over medium high heat, ensuring it doesn't burn.
Add onion.
Cook, while stirring occasionally, until onions soften and begin to caramelize, about 15 minutes.
Reduce heat to medium.
Continue to cook, while stirring occasionally, until onions are deep brown in color and well caramelized. For 12.5 lbs onion, about 60 minutes. For 25 lbs onion, about 90 minutes.
Deglaze the pan with sherry and red wines. Reduce until nearly evaporated.
Add tomato paste and Garlic Puree.
Stir together until they are evenly distributed throughout the onions.
Add Bouquet Garni, broth and beef base.
Whisk until thoroughly combined and beef base dissolves.
Bring to a boil, then reduce to a simmer.
Monitor the heat and continue to simmer, while stirring occasionally, for 45 minutes, allowing the flavors to develop. Remove from the heat.
Remove Bouquet Garni. Using a ladle, skim any scum that rises to the surface.
Season with salt & pepper. Taste and adjust seasoning as needed.
Transfer to clean food storage containers. Hold for *service.
-OR- Cool completely. Cover, label, date and store refrigerated.
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