Finely chop mushrooms by hand or put in a food processor, use pulse button to finely chop. Heat oil in a saucepan over medium heat. Add onion and seasoning, cook until soft. Increase heat to high, add mushrooms and mince, cook, stirring, for 8-10 minutes until browned. Add tomato pasatta and bring to a simmer. Reduce heat to low and simmer 15 minutes or until sauce thickens.
To make salsa, whisk oil and lime juice together in a bowl. Stir in tomatoes, avocado, capsicum, onions and coriander.
Char-grill tortillas or warm following packet directions. Divide mushroom mince mixture and salsa evenly between tortillas. Serve with chipotle mayonnaise if desired.