Switch on the oven grill on the medium setting. Brush a tray with some oil. Wash the sweet potatoes and cut them into slices about 1 cm thick. Put them on the baking tray, sprinkle with a little oil and salt. Grill in the oven on the second rack from the top for about 15 minutes.
In the meantime, wash, clean and chop the peppers for the topping. Peel and finely chop the onion. Wash the pimientos and cut about half into rings. Mix with paprika, onion, 3 tablespoons of oil and vinegar. Roughly grate the cheese and stir half into the topping. Season with salt and pepper.
Spread the topping as small heaps on the sweet potato slices. Sprinkle the rest with cheese. Spread the rest of the pimientos on the tray and sprinkle with a little oil. Grill everything on the middle shelf of the oven for about 10 minutes. Serve with tortilla chips as desired.