1cupsauerkraut(drained, lightly rinsed, and liquid squeezed out)
1avocado(peeled and sliced lengthwise into about 16 pieces (you can leave out this ingredient if you want to lower the fat content of the sandwich, and it will still be really delicious!))
Preheat oven to 450 degrees F (230 degrees C).
Spread butter on one side of each of the 8 slices of bread, and place 4 of them them butter side down on a baking sheet.
Take about half of the hummus and distribute over the 4 slices of bread.
Distribute the sauerkraut over the hummus on each slice.
Distribute the avocado slices over the sauerkraut.
For the remaining 4 slices of bread, spread hummus on the side without butter and place hummus side down on the avocado slices.
Bake in the oven for 6-8 minutes, then flip the sandwiches and bake about 6 minutes more, until the sandwiches are golden brown and crispy. (Alternatively, you can grill them on the stove top on a griddle or in a skillet).