Step 1Peel the cucumbers, cut them in half lengthwise and remove seeds. Cut the cucumbers into chunks. Puree the cucumbers in a blender with the lemon juice, onion, green pepper, salt, mint, oil and water. This makes about 2 1/2 cups puree.
Step 2Pour the cucumber puree into two 9-inch metal cake pans. Freeze.
Step 3To serve, remove the granita from freezer 5 minutes before serving. Use a fork to scrape the ice into mounds. Add the scraped ice to the gazpacho immediately before serving.