Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Rinse beans in a sieve with cold water, drain. Drain the corn. Wash coriander, shake dry, do not chop too small.
Grate cheddar. Crumble feta. Clean and wash spring onions and cut into fine rings.
Mix beans and corn with half coriander, half cheddar, half feta and half spring onions. Season with salt and pepper. Spread half of each tortillas with about 1 tbsp. sour cream and spread the bean-cheese mixture on top.
Fold the tortillas. Place them on a baking tray lined with baking paper. Brush with approx. 1 tablespoon of oil. Sprinkle with remaining cheddar and feta and sprinkle pumpkin seeds on top. Bake in a hot oven for about 10 minutes until the cheddar melts.
In the meantime, wash and halve the tomatoes for the salsa. Remove the seeds with a tablespoon while removing the stalk. Cut the tomatoes into small pieces. Mix the rest of the spring onions and coriander, 1 tablespoon of oil and lemon juice.
Season to taste with salt, pepper and sugar. Serve with quesadillas and remaining sour cream.