In a mixing bowl, add the yogurt.

Add the chopped cilantro/coriander leaves, finely chopped onion, grated cucumber, and finely chopped tomato to the yogurt.

Season with salt and pepper according to taste.

Mix all the ingredients together until well combined.

In a small frying pan, heat the oil over medium heat.

Add the mustard seeds and fry until they start to splutter.

Pour the fried mustard seeds and oil over the yogurt mixture.

Stir well to incorporate the tempered mustard seeds into the raita.

Chill the raita in the refrigerator for at least 30 minutes before serving to allow the flavors to meld.

Serve the onion, tomato & cucumber raita as a refreshing side dish or accompaniment to your favorite Indian meal.