Put onions in a bowl. Sprinkle with salt. Let sit 15 minutes. Rinse well, squeeze out water and dry well. Heat oil until hot and then fry onions for 8 to 10 minutes until browned. Stir them often so they don't burn. Drain on paper towels and set aside.
Wash greens well and remove stems. Slice coarsely. Heat oil in skillet and saute onion and garlic until they start to get soft. Add coriander, greens, lemon juice, wine and stock or water to the pan and cover and cook on low about 20 minutes. Remove the lid during the last few minutes of cooking to reduce the liquid.
While greens are cooking make sauce. Mix garlic paste into tahini and gradually add lemon juice and enough cold water to make it a pouring consistency.
Serve the greens warm covered with the onions and tahini sauce.