Drain any liquid from the tuna in to the soup bowl.
Put 2 tablespoons of mayonaisse and mix well with the tuna, breaking up and shredding any clumps of tuna
Lay two slices of bread on a plate. Put two small scoops of the tuna mixture on one of the slices. Spread and level out the tuna mixture evenly until that slice is almost completely covered.
Put the other slice of bread on top of the tuna mixture. Now your sandwich is complete and ready to eat.