1. In a bowl, dissolve salt in 1 cup (250 ml) cold water; stir in radish and carrot. Let stand at least 1 hour. Drain, squeezing out excess moisture.

2. In a small bowl, whisk together vinegar, sugar and fish sauce (if using) until sugar dissolves. Stir into radish and carrot until well-mixed. Serve sprinkled with toasted black sesame seeds, if desired. The flavor of this relish will improve over 1 or 2 days, covered, in the refrigerator.

Variations:

This salad can be made with radish alone; use 1 lb (500 g).

Replace radish with shredded white turnip and soak in salted water with carrot for at least 2 hours or overnight.

Thin slivers of fresh red chilies, or dried red chilies soaked in water until soft, can be added just before mixing with the vinegar.