For the broth
- As many beef bones as will fit in your pressure cooker
- 1/4 cup apple cider vinegar
For the onions
- As many sliced onions as will fit in your pressure cooker
- 8 tablespoons butter
- 1/2 teaspoon baking soda
For the soup
- 1 tablespoon tomato paste
- 1/2 cup all purpose flour
- 1/2 cup red wine
- 2 sprigs fresh thyme
- 1 bay leaf
- 1 teaspoon fish sauce
- 1 teaspoon apple cider vinegar
- Garlic croutons
- 1 pound gruyere cheese, shredded
- To make broth: Load pressure cooker with beef bones. Add cider vinegar and water to reach max fill line. Cook under pressure for 2-4 hours and release naturally. Remove bones and strain broth through fine mesh strainer or clean dish cloth. Transfer to refrigerator and chill until fat can be easily removed. Remove fat and discard or save for another use. (You can use this fat in place of butter to make the onions.)
- To make onions: Melt butter (or beef fat) in pressure cooker over medium heat. Load pressure cooker with onions and toss with baking soda. Cook, stirring, until onions have softened slightly and started to release liquid, about 3 minutes. Seal and cook under pressure for 20 minutes. Quick release pressure then remove lid.
- Continue cooking with lid off, stirring constantly, until liquid has completely reduced and onions are deep brown, about 5 minutes. Add tomato paste and sauté until paste begins to darken. Add flour and stir until well coated.
- Add wine and bring to simmer, scraping up any browned bits. Cook until alcohol is mostly evaporated, about 3 minutes. Add stock, plus enough water to reach 2 quarts, thyme, and bay leaf. Raise heat to medium-high and bring to a simmer. Lower heat and simmer 10 minutes.
- Add fish sauce, cider vinegar, and season with salt and pepper. Discard thyme and bay leaves.
- Serve soup topped with croutons and cheese.
This recipe is a mash-up of a number of other recipes and methods. I think this might be The One.