In a mixing bowl, combine the water, soy sauce, and brown sugar and stir thoroughly.

In a saucepan over medium heat, sauté the ginger and garlic in 1 tablespoon vegetable oil until aromatic. Approximately 1 minute.

Add the soy sauce and brown sugar mix to the ginger and garlic. Stir to combine, then bring the mix to a boil. Lower the heat and allow the sauce to simmer for 15 minutes (or until thickened).

Cut the flank steak into thin slices (approximately 1/4 inch wide), then coat the flank steak pieces with the cornstarch. Place to the side.

Heat the vegetable oil (1 cup) in a saucepan over medium-high heat.

Once the oil is hot, drop the flank steak slices into the oil (this may take two rounds). Cook the steak for 1 minute, then flip the piece. Cook for another 1 to 2 minutes until the steak is brown and lightly crispy.

Remove the flank steak from the oil and add it and crushed red pepper to the sauce. Heat the dish over medium while stirring to coat the meat (approximately 1 minute).

Place the cooked rice in a bowl, then top it with the spicy Mongolian steak. Garnish the steak with scallions and sesame seeds.