Put a deep pan of water on to boil and salt it lightly.
Peel 800g of sweet potatoes and cut them into large pieces – the size you might cut them if making for roast potatoes – then cook in a steamer basket over the boiling water for about 15 minutes, until they are approaching tenderness. Drain them in a colander and then put them in a large mixing bowl.
Preheat the oven to 200C/gas mark 6. Peel 5 large (banana) shallots and slice them in half from root to tip. Make a spice mix with a half a tsp of ground, mild red chilli, 1 tsp of dried chilli flakes and 1 tsp each of ground cumin and turmeric.
Peel and crush 1 large clove of garlic to a paste, then add to the spice mix with 2 tsp of sea salt flakes and 4 tbsp of groundnut oil. Toss the spice mix gently with the potatoes and halved shallots, then tip into a roasting tin and bake for about 25-30 minutes until the shallots are tender and sweet potatoes are lightly crisp and toasted.
Wash 2 double handfuls of spinach, then put them, still wet, in a large saucepan over a moderate heat, cover with a lid and leave to steam for a couple of minutes. Remove the lid, turn the leaves over with kitchen tongs then cover once again and continue cooking for a further minute or two until deep green and silky. Remove from the heat and drain.
Remove the potatoes from the oven, toss with the spinach leaves and, if you wish, a handful of coriander leaves. Trickle a couple of spoonfuls of yoghurt over and serve. Enough for 2
It is worth taking a little care as you mix the spices and sweet potatoes together so the potatoes don’t break up. You may find it easier to do this by hand rather than with a spoon.
Chard leaves are a more robust alternative to the spinach. They will take a few minutes longer to cook. If you wish, you could finely chop the stalks and add to the sweet potatoes as they roast.