Set instant pot to sauté mode and heat oil in the bottom. Once oil is hot, add minced garlic.
Once the garlic begins to become fragrant (about 1 minute), add ground beef, salt and pepper. Stir to break up and let slightly brown (about halfway cooked) for 4-5 minutes.
Using an oven mit, remove the pot from instant pot and drain excess fat. Return the beef and pot to the instant pot, keeping it on sauté mode. Add diced onion and green pepper and stir to combine. Allow to soften for about 2 minutes while you prepare the sauce.
In a small bowl, combine all sauce ingredients. While mixing together, don’t worry if the mustard or tomato paste doesn’t completely dissolve into the sauce, it will come together in the instant pot!
Pour sauce into the instant pot, stir to combine and close the lid. Set instant pot to manual high pressure for 6 minutes. Once done, do a slow release, allow to naturally vent and then remove the lid.
If sauce hasn’t totally thickened, press sauté again and let simmer while the excess liquid steams off. Or, slowly whisk 1/2 tbsp arrowroot flour into sauce to thicken quicker.