This recipe is based on one that found on Food.com. I made several changes and additions to the original recipe, but one things I did little to change was the sauce. This sauce is pretty much the bomb and I liked it better than the real Mongolian Beef at my local Chinese restaurant.
1 (14-ounce) package extra firm tofu, well drained and cut into strips
4 tablespoons sesame oil, divided
1 teaspoon fresh ginger, minced
2 tablespoons garlic, minced
1 cup low sodium soy sauce
1 cup water
1 1/4 cup brown sugar
1/4 cup cornstarch
1/2 large onion chopped
10 ounces slice white mushrooms
1 package beef like vegan meat substitute (like the meatless beef from Trader Joe's)
Cut and drain your tofu. See the post, How to Drain Tofu for specifics. While the tofu drains, warm 3 tablespoons of sesame oil in a large skillet over medium heat. When the oil is warm add the ginger and garlic, cooking until fragrant, about 30 seconds. Do not let the garlic burn. Add the soy sauce and water. Slowly add in the brown sugar and stir until the sugar is all dissolved. Bring the mixture to a slow boil and cook until the sauce has reduced just a bit.
While the sauce is reducing warm one tablespoon of sesame oil to another skillet, to this add the oil and cook until the onion in slightly tender and has released some of its moisture. Remove the onion from the skillet and set aside. Add the mushrooms to the still warm skillet and cook them until they are brown and have released all their liquid.
The sauce should be reduced just a bit by now. To the sauce add the cornstarch and stir with a whisk until the cornstarch is 100% incorporated into the sauce. The sauce should thicken almost immediately. Reduced the heat to low, and add in the onions, mushrooms, tofu sticks, and beef-like meat substitute. Stir until everything is well coated and allow to cook together for 10 minutes or so until all the flavors are combined.