1. Puree cucumbers in a food processor.
2. Continuing to puree, add the yogurt and lemon juice.
3. Transfer to a large bowl and add the bell peppers, onion, chili peppers, cilantro, scallions, coriander and cumin. Add salt and pepper to taste.
4. Add a few sprigs of cilantro or a small dollop of yogurt as a garnish, if desired.