Heat the oil in a wok or medium frying pan over medium heat.
Once the oil is shimmering, add the mustard seeds, urad dal, and chana dal. Sizzle for about 30 seconds until the mustard seeds begin to pop and the dals turn a lovely golden-red.
Immediately add the broken red chilies and curry leaves—be careful, they will splutter! Give it a quick stir, then add the chopped onion.
Sauté for about 5 minutes, until the onions are soft and translucent.
Turn the heat down to medium-low.
Add the diced cooked beets, salt, finely chopped green chilies, and grated coconut to the pan.
Stir everything together for about a minute to coat the beets in the spices.
Pour in 4 tablespoons (60 ml / 2 fl oz) of water and cook gently on low heat for 10 minutes, stirring occasionally, allowing the flavors to meld. The water should fully evaporate; if any remains, increase the heat for a moment to cook it off.
Stir in the fresh cilantro and serve warm.
Don't skip the fresh or frozen coconut! It adds a crucial sweetness and texture that balances the earthiness of the beets and the warmth of the spices.