Steps
1. Slice the whole grain sandwich roll in half horizontally.
2. Spread hummus generously on both halves of the roll.
3. Layer the cucumber, tomato, red bell pepper, and avocado slices on one half of the roll.
4. Add fresh spinach leaves on top and season with salt and pepper.
5. Drizzle with olive oil and lemon juice if desired.
6. Top with the other half of the roll, press down gently, and cut in half for serving.