Steps
1. Slice the sandwich bun in half.
2. Spread hummus on both sides of the bun.
3. Layer mixed greens, cucumbers, tomatoes, red onions, and feta cheese on the bottom half of the bun.
4. Drizzle olive oil and balsamic vinegar over the veggies.
5. Season with salt and pepper.
6. Cover with the top half of the bun.
7. Serve and enjoy!