Caramelized Onion Soup

2 tablespoons butter or
1 tablespoon butter, and
1 tablespoon olive oil
3 large yellow onions, thinly sliced (about 4 cups)
2 large cloves garlic, minced
2 tablespoons tomato paste
½ cup dry sherry or
Maderia wine
1 tablespoon Dijon mustard
½ teaspoon dried thyme
1 small bay leaf
½ teaspoon salt, or to taste
3/4 teaspoon sugar
freshly ground black pepper, to taste
3/4 teaspoon dried oregano
1 (16-ounce) can beef broth
2 (16-ounce) cans reduced sodium chicken broth

1. In a large Dutch oven or soup pot, melt butter and saute onion slowly, until they are golden and caramelized. (Stir infrequently - every 10 minutes- to encourage caramelizing. This will take about 30 minutes).

2. Add garlic and tomato paste. Stir in for about 2 minutes. Add remaining ingredients, stir well. Simmer over low heat for at least 30 minutes and up to 1 hour.