Take out spring roll wrappers if frozen to let thaw. Heat oven to 375 °F.
Prepare the veggies (can use a box grater or the shredding attachment of a food processor) and crumble the tofu. Then heat a large wok or frying pan on high heat.
Add the tofu to the pan with 2 tbsp soy sauce, 2 tbsp sesame oil and 1 tbsp mirin. Cook for a few minutes to crisp up the tofu then remove it from the pan.
Add 2 tbsp cooking oil to the pan then the onion and garlic. Cook for 2 minutes.
Add the mushrooms and cook 4-5 minutes. Add cabbage and carrots, then cook another 8 minutes or until the veggies are cooked down and there is minimal water in the bottom of the pan. You may need to strain excess water away.
Reduce heat to medium-low and stir in 1 1/2 tbsp sugar, 3/4 tsp black pepper, 4 tbsp soy sauce, 2 tbsp sesame oil and cook for another 1-2 minutes. Add the cooked crumbled tofu to the pan and mix together. Remove from heat after excess liquid has evaporated.
Let your filling cool before rolling the spring rolls. To roll, place 3 tbsp of the veggies onto the bottom half of the wrapper, fold 2 opposite corners over the middle so they meet in the middle and cover the filling, then pick up the bottom corner of the wrapper (closest to you) and roll it over the filling until the roll is closed.
Bake rolls on a parchment lined baking sheet for a total of 12-15 minutes, flipping halfway through.