Heat olive oil in a pot. Add garlic and onion, sauté for 3 minutes. Add water or vegetable broth, lemon juice and lemon zest, boil then simmer for 5 minutes. Add peas and cook for 3 more minutes. Let cool a little and blend in a blender until smooth. Return to the pot and reheat. Add salt and sugar. Pour into serving bowls. (Optional) Garnish with parsley flakes, chopped green onions or other herbs.