In a small bowl mix together tuna, spring onion, celery, chili garlic sauce, mustard and mayo. Season with a little freshly ground pepper. Set aside.
(This step is OPTIONAL*) Prepare a nonstick pan on low heat. Warm each tortilla in a pan on low heat for about 6-8 seconds on each side.
Transfer each tortilla onto a plate.
Spread half of tuna mixture on each tortilla, leaving 1/2 inch space on the edges. Arrange spinach leaves on top of tuna, covering just half portion of tortilla.
Slice the avocado thinly to about 1/8 inch thick. Arrange avocado slices next to the spinach,, covering the other half of the tortilla. Roll it gently to fold 3 times. Cut wrap in half and serve immediately.
*Warming the tortilla is optional. You can use cold tortilla wrap right out of the package.