Spread refried bean mixture on one slice of bread. Top with shredded vegan cheddar. Top with other slice of bread.
Spread 1 teaspoon vegan mayo on the outside of one of the slices of bread. Place face down in a pan. Spread the other teaspoon of vegan mayo on the other piece of bread (the side facing you). Cook over medium heat until golden brown on both sides.
Notes
Refried beans will last about 4 days. If you don't think you'll eat them up in that time, you can freeze them in a freezer bag for 1-2 months.