Wash and clean the spring onions and cut them into thin rings. Drain the cucumbers and cut them into very small cubes. Mix soured milk, mustard, onion rings and cucumber cubes. Season with salt and pepper.
Quarter the peppers lengthwise, remove seeds, wash and dab dry. Rinse tomatoes and pat dry. Rinse chicken meat, dab dry and cut into large cubes. Alternate meat, pepper quarters and cherry tomatoes on skewers.
Spread a thin layer of oil on the chicken skewers, sprinkle with salt and pepper all around and place on the preheated grill. Grill on low heat for 10-15 minutes, turning several times. After 5 minutes, place the remaining quarters of paprika on the barbecue and cook with it.
Rinse basil, dab dry, pluck leaves. Arrange skewers with the basil leaves. Add sauce.