Turn on the broiler and set the oven rack 6 inches from the heating element. Place oxtails in a large bowl and add 1 tablespoon Magic Mushroom Powder or Diamond Crystal kosher salt.
Toss well and and arrange in a single layer on a rimmed baking sheet.
Pop the oxtails under the broiler. Broil for about 5 minutes on each side or until nicely browned. Alternatively, you can brown the meat in batches in the Instant Pot on the “Sauté” function, but it’ll be tedious and messy.
While the oxtails are browning under the broiler, grab your Instant Pot and turn on the “Sauté” function. When the metal insert is hot, add the ghee or fat of choice. Toss in the sliced onions and carrots and cook until the onions are softened.
Sprinkle on some additional Magic Mushroom Powder or kosher salt. Toss in the smashed garlic, and stir for about 30 seconds or until fragrant.
Grab the browned oxtails off the pan, and nestle them into the vegetables. Pour in any accumulated juices from the pan. Remember not to fill your pressure cooker more than 2/3rds full!
Pour the marinara sauce, fish sauce, and aged balsamic vinegar onto the meat. Stir well, making sure the liquid reaches the bottom of the pot.
Lock on the lid and program the Instant Pot to cook under high pressure for 45 minutes.
When the oxtails are done cooking, let the pressure release naturally. If you’re impatient, you can release the pressure manually after 30 minutes has elapsed.
The meat should be tender and falling off the bone. Taste the stew and adjust the seasoning with salt, pepper, Magic Mushroom Powder, and/or balsamic vinegar if needed.
I love serving the oxtails directly on raw spiralized zucchini (a.k.a. zoodles) because the hot sauce cooks the zucchini without making them super watery and soft.