In a bowl, combine your Tuna, Mayo, Mustard, Onion, Parsley, Garlic, Seasoning, Cayenne Pepper and Lemon Juice. Place to one side.
Half, destone and slice your Avocado into evenly sized strips (8 strips per half). Half your Tomatoes and slice to similar thickness. You should end up with 16 slices of Avocado and 16 slices of Tomato.
Evenly slice your bagels in half and toast either under the grill or in toaster.
Assemble by placing a a slice of Avocado on the bagel, then a Tomato slice and repeat in a circular pattern. 4 slices of each should cover the surface.
Sprinkle a little Salt and Pepper and drizzle a bit of Olive Oil. Top with Tuna then finish with Cheese.
Grill unto golden and bubbly on top. Serve with an extra squeeze of Lemon Juice and a sprinkle of Parsley.
a) If you don't have bagels then a thick slice of toast will work just as perfectly!