In a large (8-cup) glass measuring cup, or glass bowl, heat the chicken stock, sherry and soy sauce in a microwave for 3 minutes on HIGH.
Stir in onions and thyme, and microwave for an additional 2 minutes.
Taste, and adjust seasoning as needed with black pepper and, if you're using homemade stock, kosher salt.
Serve hot, with a grilled cheese sandwich on the side.
*If you don't have a slow cooker, you can caramelize onions on the stove top: Thinly slice 3 large yellow onions, and sauté them in 2 Tbsp olive oil over lowest heat for 30-45 minutes, until they are brown and tender.