Sweet potato nachos

4 medium sweet potatoes (around 600g), peeled and sliced into 5mm thick coins

1tbsp light olive oil

1tsp salt

60g Cheddar cheese, grated

4tbsp low-fat natural yoghurt, to serve

For the spiced mince:

1tbsp oil

1 red onion, diced

100g veggie mince (or minced beef)

½tsp ground cumin

½tsp ground coriander

½tsp smoked paprika

Pinch of chilli powder

130g frozen sliced bell pepper (or the same amount of fresh, sliced)

For the refried beans:

400g tin of black beans, drained but liquid reserved

Pinch of salt

1tsp ground cumin

For the salsa:

200g cherry tomatoes, roughly chopped

Big handful of fresh coriander, finely chopped

Juice of 1 lime

Pinch of salt