Slice mushroom caps into 1/2 inch pieces. Sauté in a skillet until the mushrooms liquid has evaporated.
Whisk together tamari, rice vinegar, brown sugar, 1 tsp sriracha, sesame oil, ginger, garlic, and corn starch. Pour over mushrooms in the skillet and stir until thick and the mushrooms are well coated.
Combine mayo with remaining 1 tsp sriracha until smooth.
Heat corn tortillas according to package directions.
Top each tortilla with red cabbage, mushrooms, queso fresco, cilantro and sriracha mayo. Serve.