Sprinkle the steak on all sides with cornstarch, toss to coat. Allow to sit at room temperature while you prepare the sauce.
Heat the olive oil in a saucepan over medium high heat. Add the ginger and garlic, stir for 30 seconds.
Add the soy sauce, stout and brown sugar, simmer for 5 to 10 minutes.
Heat the canola oil in a skillet over medium high heat. Add the steak, cooking until browned on all sides (the steak does not need to be cooked through). Pour off excess oil.
Add the sauce, simmer until thickened.
Add to a serving plate, sprinkle with green onions.