Peel cucumber; cut in half lengthwise and scrape out seeds. Cut in chunks.

Cut pepper and onion (if using) in chunks. Put in blender or food processor with one cup tomato juice. Process until vegetables are coarsely chopped.

Place in bowl, add garlic powder, onion powder (if using), lemon juice, oil, rest of tomato juice and salt.

Taste to see if you want more lemon juice or salt.

Chill several hours or overnight.