Prepare you flank steak by slicing against the grain into very thin strips (about 1/4-1/2 inch thick).
If you want to sear your meat, turn your Instant Pot to saute. Once it reads "HOT," add in 1/2 -1 tablespoon oil and let heat for 1 minute. Add in beef and saute until JUST browned. About 2 minutes.
Mix together the soy sauce, pineapple juice, honey and seasonings and add to Instant Pot.
Put lid on Instant Pot and turn vent knob to the sealed position.
Hit manual (you will have to first turn the Instant Pot OFF from Saute function) and then adjust the cook time by using the plus or minus buttons to 3 minutes.
After cook time has elapsed, let rest 5-10 minutes and then do a quick release.
Turn Instant Pot back to saute. Make a cornstarch slurry by mixing cornstarch with 2 tablespoons water until fully combined. Add cornstarch slurry to pressure cooker and stir and boil for 2-3 minutes.
Turn off instant pot and serve Mongolian Beef with rice, cauliflower rice and top with scallions or sesame seeds if desired.