From The Indian Grocery Store Demystified, by Linda Bladholm (2000), via Epicurious.
1 medium cucumber
1 teaspoon cumin seeds
2 cups plain, whole-milk yogurt
1 clove garlic, peeled and minced
2 tablespoons fresh coriander or mint leaves, chopped
cayenne or paprika to garnish
Peel cucumber. Cut lengthwise into 1/4-inch strips, then into thin slices crosswise. Blot off moisture with paper towels. Toast cumin seeds for a few seconds in a small, heavy frying pan over high heat. In a bowl, stir yogurt until it is smooth. Mix it with the cumin, garlic and coriander or mint leaves. Combine mixture with cucumber slivers, sprinkle with cayenne or paprika, and chill before serving.