Wash potatoes thoroughly, dab dry and cut in half. Place the potatoes on a baking tray lined with baking paper. Sprinkle with salt and cook in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: level 2) for 40-50 minutes.
In the meantime wash and clean the tomatoes. Cut 1 into pieces and puree it with the chopping stick. Quarter the remaining tomatoes and remove seeds. Cut the flesh into small cubes. Peel garlic, press it through a garlic press and add it to the tomato puree.
Wash and halve the chillies and remove the seeds. Chop the pod finely and fold into the puree with the diced tomatoes. Wash the chives, dab dry, cut into fine rolls and add to the tomatoes.
Add vinegar and oil and season to taste with salt, pepper and sugar. Remove the potatoes and let them cool down briefly. Cut cheese into strips. Spread the pesto on the potatoes and cover with cheese in a grid pattern.
Grate the potatoes under the grill of the oven until golden brown. Arrange potatoes on a preheated plate, garnish with basil. Add tomato dip.