Get the curry going first. In a wide, heavy-based pan, fry the onion in the oil with a lid on to soften for about 5 minutes. Stir in the sweet potato chunks, curry powder, and turmeric, and fast-fry with the lid off until it begins to stick to the bottom.
In two batches, stir in the spinach, adding the ground almonds and chilli. When all the spinach is in the pot and beginning to collapse, pour in the coconut milk, add some salt, stir well and put the lid back on.
Keep it at an active simmer, stirring from time to time, for about 20 minutes until the spuds are cooked. Take the lid off and let the curry reduce down to a thicker consistency (another 10 minutes or so).
For the dhal, gently fry the garlic and all the seeds (don't forget the cardamom) in the oil until they are a deep golden brown. Tip in the split peas and give them a good roll around in the garlicky oil then pour in 1l of water and turn the heat up.
Slowly bring it to a gently boil over around 10 minutes then skim, cover and leave to simmer for 45 minutes-1 hour until the peas are well-cooked. Taste for seasoning - dried pulses take a lot of salt to reach their flavour zenith.
Finish the curry by stirring in the lime juice and adjusting the seasoning. Serve with the dhal on the side and all the usual suspects (basmati rice, chutney, and yoghurt).