1. Preheat the grill to medium-high heat.
2. In a mixing bowl, combine olive oil, garam masala, cumin powder, coriander powder, and salt.
3. Coat the chicken breasts with the spice mixture.
4. Grill the chicken for about 6-7 minutes on each side, or until fully cooked.
5. Let the chicken rest for 5 minutes, then slice it.
6. In a large bowl, combine mixed greens, cherry tomatoes, cucumber, and red onion.
7. Add the sliced chicken on top of the salad.
8. Drizzle with lemon juice and serve immediately.