Slice the Roma tomato, mini cucumber, red onion, and roasted red pepper to about 1/4 inch thick.

Spread a generous layer of hummus on one side of each slice of whole wheat bread.

Layer slices of red onion, roasted red pepper, cucumber, and tomato on the hummus-covered slice, followed by a handful of arugula.

Place the second slice of bread, hummus side down, on top of the layered vegetables and press down gently.

Cut the sandwich diagonally for easy handling and serve immediately.