(Optional) Pit, peel and mash the avocado. Mix in the avocado toast seasoning, if using.
Spread butter across one side of each bread slice.
Heat up a frying pan (or sandwich press, or other preferred cooking surface). You’ll know it’s ready when you can sprinkle a drop of water on the surface and it dances around. Reduce the heat to medium.
Place both slices of bread butter-side down in the pan. (If using a sandwich press, place just one slice down.)
(Optional) Spread the mashed avocado on one or both slices of bread.
Place your cheese slice(s) on top of one bread slice.
Spread the “tuna” salad on top of the other bread slice. Use a spatula to squash it down if you have to.
(If using a sandwich press, place the tofuna salad on top of the cheese slice, then place the other slice of bread on top of the sandwich.)
If using a frying pan, cover with a lid for 1–2 minutes to help the cheese melt.
Cook until the bread slices are golden-brown on the buttered side.
If using a frying pan, remove the lid and use a spatula to move your bread slices to a plate, and put one of the slices face-down on top of the other. The avocado helps here — In addition to being delicious, it helps keep the cheese and tofuna from sliding off during this step.
If using a sandwich press, all you have to do is use a spatula to move the sandwich onto a plate. Easy!
Cut the sandwich into triangles, objectively the tastiest shape, and optionally serve with some vegan tomato soup.