Cook the brown rice according to the package instructions.
Thinly slice the flank steak against the grain; mince garlic and ginger.
Turn on the Instant Pot and press the "Saute" button; once hot, add the steak and brown on all sides.
Meanwhile, whisk together the soy sauce, garlic, ginger, and water.
Once the meat is browned, pour soy sauce mixture over it. Lock on the Instant Pot Lid.
Cancel the "Saute" feature, and push the "Manual" button. Adjust the time for 12 minutes.
While the beef is cooking, whisk together the honey and molasses in a small dish.
In another small dish, whisk together the cornstarch with 3 tablespoons of cold water.
When the Instant Pot beeps, use the vent to release the pressure all at once, then carefully open the lid.
Stir in the honey/molasses mixture, followed by cornstarch/water mixture.
Push the "Saute" button and heat the beef just until the sauce thickens, 3-5 minutes.
Serve the Mongolian beef over the brown rice, garnished with chopped green onions, with the steamed veggies on the side.
For the Veggies: Peel carrots and slice thinly on a diagonal. Cut broccoli into florets.
Add all the veggies to a steamer basket along with 1/2 cup water. Steam until tender; season with salt and pepper if desired.