Let them rest here to they release liquid while you prep the rest.Mince onion and garlic, add in to the casserole dish.Thinly slice mushrooms and add them to the dish too.Open and drain tuna cans, flake the tuna into the casserole dish.Add in the salt, pepper, 1 tbsp mayo, mustard, lemon juice and rosemary.Mix well.Wrap the kitchen towel around the zucchini and squeeze the water out.Add the zoodles to the casserole dish and toss to combine.Pour in the cashew cream.