Put the oil, mushroom, onion, tomato and garlic in the Medium Classic Roaster and fry for 5 – 8 minutes in the microwave on high. Drain the tuna and add to the fried vegetables. Add the cheese, keeping some to sprinkle over the wraps later. Divide the mixture between the 8 wraps and roll it up. Arrange in the Large Rectangular Roaster.
Prepare the sauce:
Mix the flour with a little bit of the chicken/fish stock to make a paste and then add the rest of the broth and the garlic. Microwave on high until cooked. Add salt (and/or flavourings) and sour cream. Pour over the wraps. Sprinkle with the leftover cheese. Turn on the oven at 160 ºC and bake uncovered for 30-45 minutes or until done.