Sweet potato, red onion and chickpea tray bake

This sweet potato and chickpea tray bake cooks on a single tray at one oven setting, so there is little washing-up. Sweet potato, red onion and a tin of chickpeas roast together until the edges catch, and a spoon of lemony yoghurt goes over the top.

If your oven has room, roast a second tray at the same time and keep it for the next day's lunch boxes. You heat the oven once for two meals.

Ingredients for the tray bake

• 3 medium sweet potatoes (about 900 g), cut into 2 cm cubes
• 2 red onions, cut into wedges
• 1 tin (400 g) chickpeas, drained, rinsed and patted dry
• 3 tbsp vegetable or olive oil
• 1 tsp ground cumin
• 1 tsp smoked paprika
• A few sprigs of rosemary, or 1 tsp dried
• Salt and pepper
• 150 g plain yoghurt
• 1 lemon
• A handful of salad leaves or a slice of bread, to serve

Method

1. Heat the oven to 210°C (190°C fan, gas 7).
2. On a large tray, toss the sweet potato, onion and chickpeas with the oil, cumin, paprika, rosemary, salt and pepper. Spread everything in a single layer; use two trays if it is crowded, or it will steam instead of roast.
3. Roast for 30 to 35 minutes, turning once halfway, until the sweet potato is tender and browned at the edges.
4. Meanwhile, mix the yoghurt with a squeeze of lemon and a pinch of salt.
5. Serve from the tray with the yoghurt spooned over and the rest of the lemon cut into wedges.

Budget swaps

• Sweet potatoes priced high? Use half ordinary potatoes or squash, which are often lower per kilo in autumn.
• Dried chickpeas cooked in a batch usually cost less per serving than tins. Freeze them in 240 g portions, roughly one drained tin; the soak-and-simmer steps are much like those in our red beans from dried.
• A pot of rosemary on the windowsill outlasts several cut packs.
• Any seeds already in the cupboard add crunch in place of a bought topping.

Storage and leftovers

Keeps for 3 days in a covered box in the fridge. Eat it cold as a salad with leaves, or reheat it in a hot oven for about 10 minutes. It doesn't freeze well, because the sweet potato turns soft, so cook only what will be eaten within three days. For lunch boxes that do freeze, see the oven meatball batch boxes, which use the same roasting method for the roots.