Saute zucchini and scallions in olive oil until brown but still firm. Place in bowl and stir in cheese, dill, and pepper. Add egg yolks and flour to zucchini mixture and stir until just blended. In a separate bowl, beat egg whites with salt until stiff peaks form, and then gently fold into zucchini mixture. Drop 1/4 cup of mixture into hot skillet with a thick layer of cooking oil. Fritters are done when the outside is brown and the inside is moist.