In a separate bowl. Add the corn starch and water then whisk it together. Add and stir in the mustard and set aside.
Take the multicooker, open and unlock the lid by turning the handle to the unlock position. With the lid still open, turn the handle to the lock position.
Press the [MENU SELECTION] button and select the [OVEN] function. Set the cooking time for 30 minutes and temperature 120 degrees then press [COOK]
Add oil into the cooker. Add shrimp and stir until its cooked. Season with salt and pepper. Once cooked, take it out and set it aside on a plate
Add onion, green bell pepper and garlic. Stir-fry until the onions are translucent. Add the cooked shrimp back then add apple cider vinegar to deglaze. Add the mustard mixture and bring it to a boil. Stir constantly. Add lemon juice into the cooker.