Toast the peanuts or cashews for the gremolata for a minute in a large, deep-sided saucepan until golden and set aside.
Make the curry paste by blitzing the garlic, onion, lemongrass, chilli and ginger in a food processor – it doesn’t need to be totally smooth.
Add the spices to the pan you used for the nuts and let them toast for a minute, then add the curry paste and the ghee or oil and fry gently for 5 minutes.
Meanwhile chop the squash into 2cm chunks. I don’t bother peeling it, just remove the seeds.
Add the squash and lentils to the pan with the coconut milk and stock or broth. Give it a stir, then pop a lid on and let simmer over a medium heat for about 25 minutes or until the squash is tender. Stir every 5 minutes or so, watching out so the lentils don’t catch on the bottom of the pan, and adding more liquid if it looks dry or if you like it soupier. Season with tamari, fish sauce or a little salt.
While the curry is cooking, make the gremolata. Add the toasted nuts to the food processor (no need to wash it out from earlier) with all the other ingredients and pulse until just chopped – it should be drier and chunkier than a pesto and full of flavour and tang. Serve the curry with a good dollop of gremolata on top.