Finely chop the peas, chickpeas and onion together in a blender or food processor. Alternatively, chop them finely with a knife. Mix in the crushed seeds, turmeric, mint and seasoning.
Spoon 20 mounds of the mixture on to a baking sheet, then roll into ovals with the palms of your hands. Mix the sesame seeds and flour on a plate, then roll the falafel in the mixture and return to the baking sheet. Cover and chill until required.
Mix all the cacik ingredients together, season to taste and spoon into a serving bowl. Cover and chill until required.
When ready to serve, heat 2 tablespoons of the oil in a large frying pan, add the falafel and fry, turning, until golden brown and piping hot, adding the remaining oil if needed. Serve immediately with the cacik, a green salad and warmed pitta breads.