Select Sauté on the Instant Pot, press Start, and heat the oil. Add the shallot, garlic, and 1/4 tsp pepper and cook, stirring occasionally, until fragrant, about 1 minute. Add the ground pork and 1 tsp of the soy sauce and cook, breaking up the meat with a wooden spoon and stirring occasionally, until the pork has started to release some fat, 2–3 minutes. Add the cabbage, carrots, mushrooms, fish sauce, sugar, the remaining 2 tsp soy sauce, and 1/2 tsp salt and cook, stirring occasionally, until the cabbage has wilted and the pork is cooked through, 3–4 minutes. Press the Cancel button to reset the program.