Cook beetroots by boiling or steaming until tender, then peel and shred them using a grater.
In a large bowl, whisk the yogurt until smooth and creamy.
Add the shredded beetroot to the yogurt and mix well.
Season with salt and cumin powder, mixing thoroughly.
If using optional vegetables, add chopped onion, green chili, and carrot to the mixture.
For tempering (optional): Heat oil in a small pan, add mustard seeds and let them splutter, then add curry leaves and asafoetida. Pour this over the raita.
Mix all ingredients gently and adjust seasoning if needed.
Chill in the refrigerator for at least 30 minutes before serving.
Garnish with fresh herbs before serving.