|Makes 12 generous servings
6 tablespoon butter
Heat butter and olive oil in a 10 quart heavy bottom pot. Sauté onions over medium heat until translucent, 15-20 minutes.
Add water, coffee, vinegar, sherry, beef stock concentrate and spices. Simmer for 45 minutes.
For each serving: Toast one slice French bread. Place toast in bowl, fill bowl with soup. Add 1/4 cup Gruyere cheese and 1 Tbsp grated Parmesan cheese. Place soup bowls under broiler until cheese melts. Serve immediately.
Recipe shared with permission from Tiber Canyon.