Start with some nice thick plain yogurt.
Then grab half a cucumber, split it down the middle and scoop out the seeds and chop finely.
Add the cucumber to the yogurt and a teaspoon of white vinegar, a teaspoon of olive oil, a small clove of minced garlic ad 1/4 teaspoon salt.
Mix it all together and chill until you are ready to serve.
Tzatziki (from Odyssey of Greek Cooking)
1 cup yogurt, thick
1/2 cucumber, peeled, seeds scooped out and chopped fine
1 tsp. white vinegar
1 tsp. olive oil
1 small clove garlic, minced
1/4 tsp. salt
Mix all the ingredients together until thoroughly combined.