- 3 lbs. yellow onions, sliced 1/8 inch thick
- 4 cups unsalted beef stock, divided
- 1 and 1/2 tsp. salt, divided
- 3 Tbsp. butter, melted
- 1 Tbsp. brown sugar
- 1/4 tsp. baking powder
- 1 Tbsp. butter
- 1/4 tsp. pepper
- 1/4 tsp. dried thyme
- 2 Tbsp. sweet sherry (optional)
- 6 slices toasted bread
- 2 cups shredded Swiss cheese
- Measure 1 cup of the beef stock into the Instant Pot. Put a steamer basket on top of the liquid.
- Add the sliced onions to the steamer basket. Sprinkle with 1 teaspoon of the salt and drizzle with the melted butter. Toss it all gently with your hands.
- Set the valve to Sealing and set the Instant Pot to pressure cook on high for 3 minutes. After it has finished the 3 minutes, do a quick release by turning the valve to Venting.
- Once the steam has all escaped and the button has dropped down, remove the lid. Strain the onions through sieve with a bowl placed under it (so that you catch those delicious juices!). Note that the onions will be soft and tasty now. You can totally stop here. Or…
- Sprinkle the onions with the brown sugar and baking powder. Toss gently.
- Set the Instant Pot to Sauté on high. Add the unmelted butter. Once melted, add the onions. Pat them down.
- Cook the onions without disturbing them. Every couple of minutes, scrape some up and see if there is browning underneath. If so, give them all a stir, being sure to scrape any brownings from the bottom.
- Continue to cook and stir as directed until onions have reached desired color, about 10-12 minutes.
- Add the remaining 3 cups of beef stock, the remaining 1/2 teaspoon of salt, the pepper, the thyme, and the sherry (if using). Stir and make sure nothing is stuck to the bottom of the pot. You can get a burn notice from your Instant Pot if any of the onions or brownings are still there.
- Put the lid onto the Instant Pot and set the valve to Sealing. Set the Instant Pot to cook on high pressure for 1 minute.
- Preheat the broiler.* Arrange 6 oven-safe soup bowls on a sheet pan. Toast the bread.
- Once the Instant Pot has finished pressure cooking, turn the valve to Venting. Once the steam has all escaped, remove the lid. Ladle the soup into the bowls.
- Top each bowl with a slice of toast and 1/6 of the cheese. Put the pan of bowls under the broiler just until the cheese has melted. Remove pan from oven and serve soup.
*Note: There is an alternative to using the broiler. You’ll use croutons instead of toast because they’re harder and won’t get as soggy. Fill the soup bowls 2/3 full of hot soup. Put 6-8 croutons into each bowl. Top each with 1/6 of the cheese. Ladle more soup over the croutons and cheese to help melt the cheese. Serve immediately.