Add all the ingredients listed under “Chutney” to a mixer jar and grind until smooth.
Heat coconut oil. Add mustard seeds, urad dal, red chilli, curry leaves, and asafoetida; let them splutter. Pour the tempering over the chutney and mix well.
You can use a small piece of tamarind instead of lemon juice.
If using regular cucumber, peel the skin before grinding.
Serve with idli, dosa, paniyaram, or even as a refreshing dip with snacks.