Mix the wheat flour, rye flour, sourdough starter, water, salt and olive oil into a dough. Knead until smooth, cover and let ferment slowly for about 24 hours.
Divide the dough into 8 small burger buns. Let them rest briefly, sprinkle with sesame seeds and bake at 200°C until golden.
Slice the tofu into thick pieces. Mix soy sauce, olive oil, honey, garlic and sesame seeds, then marinate the tofu for at least 2 hours.
Sear the tofu in a hot pan until golden and slightly crispy on both sides.
Lightly sauté the mushrooms and onions until soft and lightly caramelized.
Mash the avocado with a little salt, pepper and lemon juice if desired.
Slice the buns, spread avocado on the bottom half and layer with cucumber, tofu, mushrooms, spring onions and Chinese cabbage.
Serve immediately while the tofu stays crisp and warm.