Sauté: Select the sauté function on the Instant Pot and add 1 tablespoon of vegetable oil to the pot. When the pot is hot, add the sliced onions and 1 tablespoon of butter. Cook, stirring, until the onions are lightly browned. Add the garlic and sauté for an additional 1 minute. Remove the onions and garlic to a plate and set aside. Add the remaining vegetable oil and butter to the pot, then adjust the sauté function to high (or higher). Add the beef and sprinkle with salt and pepper. Cook the beef cook, stirring, until it is well browned on all sides.

Deglaze: Add the beef broth and beer to the pot, scraping up any browned bits. Add the onions back to the pot along with the bay leaves and thyme.

Pressure Cook: Secure the lid and set the steam release vent to the sealing position. Choose pressure cook (high) and set the time to 35 minutes. When the time is up, let the steam release naturally for 10 minutes, and then carefully release the remaining pressure. 

Add the Remaining Ingredients: Switch to the sauté mode and add the thawed pearl onions, vinegar, and brown sugar. Cook, stirring occasionally, for 3 minutes.

Finish and Serve: In a small bowl or cup, combine 2 tablespoons of cornstarch with water to form a slurry. Stir the slurry into the beef mixture and continue cooking until the stew has thickened. Taste and adjust the seasoning with salt and pepper. Serve the beef over noodles, potatoes, or rice. Enjoy!