Remove tofu from its tube wrapping. Slice into 1/2-inch thick rounds. Dust with cornstarch.
Heat oil in a non-stick skillet over medium-high heat. Pan-fry tofu until golden brown on both sides, about 4-5 minutes.
Remove tofu from pan. Add tomato and cook until soft, about 3 minutes. Add ketchup, mirin, soy sauce, sugar, stock and sesame oil. Add assorted mushrooms and stir to combine. Return tofu to pan and simmer for 2 minutes.