In a food processor, purée tomato until almost smooth. Add cucumber, onion, garlic, both vinegars, oil, salt, and pepper and pulse until almost smooth. Add more vinegar, salt, and pepper to taste. Chill soup in refrigerator for at least 30 minutes; the longer it sits the more the flavors will develop. Store gazpacho tightly sealed in coldest part of refrigerator for up to 2 days.