Put oil in a large skillet over medium heat. Then add onion, salt, pepper and stir occasionally until onion wilts. Add beans, about half the dill and 1 cup water. Lower the heat, cover and adjust to a simmering status. Cook for 20 to 30 minutes. Uncover and rais the heat so any excess liquid boils away. Add lemon juice. Turn off heat. Stir in yogurt and mix with remaining dill.