- Cut ends off zucchini and roughly chop, leaving on the skin. Roughly chop onion.
- Saute onion and zucchini in oil with red pepper flakes until softened and beginning to brown, about 10 to 12 minutes. Set aside to cool.
- When cool, place the onion/zucchini mixture in a food processor or blender with all other ingredients and puree until very smooth and a pretty, pale green. Garnish with large garlic croutons, if desired.