Rich Onion Soup Base
A proper onion soup depends entirely on how far you push the onions. You are looking for a transition from pale gold to a dark, jammy brown, which provides the backbone for the entire dish.
Patience is your primary ingredient
Do not turn up the heat to speed up the process. High heat will burn the onions instead of sweetening them.
- heavy-bottomed Dutch oven
- wooden spoon
- tongs
What goes in.
- 3 lbyellow onions, halved and sliced into thin half-moons
- 4 tbspunsalted butter
- 1 tbspolive oil
- 1/2 cupdry sherry or white wine
- 6 cupshigh-quality beef stock
- 2fresh thyme sprigs
- 1 tspkosher salt
Caramelization is not just browning
The onions should reduce by three-quarters in volume and turn a dark, consistent brown. If the bottom of the pot develops a dark brown film, that is the foundation of your flavor.
The method.
Melt the butter and oil
Place the Dutch oven over medium heat. Once the butter foams, add the onions and salt.
Cook down the onions
Stir every 10 minutes. After 45 minutes, they will be soft and gold. Keep going for another 30 to 45 minutes, stirring more frequently to prevent burning, until they are deep brown and jam-like.
Deglaze
Pour in the sherry. Use the wooden spoon to scrape the brown bits off the bottom of the pot. Cook until the liquid has almost entirely evaporated.
Simmer
Pour in the beef stock and add the thyme. Bring to a gentle simmer and let it cook uncovered for 20 minutes to marry the flavors.
When it doesn't go to plan.
Use a mix of yellow and red onions for a more complex sweetness.
If the onions catch on the bottom too quickly, add a tablespoon of water to pull the fond back up.
The soup base can be made a day ahead; the flavor will deepen in the refrigerator.
The ones that keep coming up.
How dark should the onions be?
They should look like dark leather. If they are light yellow, they are not finished.
Can I use vegetable stock?
You can, but the result will be significantly lighter in flavor and color. Beef stock is standard for the traditional depth.
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