Place the Swiss chard stalks in a pan and cover with water. Add sugar upon boiling, cover up and cook over low heat for 25 15 minutes or until tender. Drain to remove the excess liquid.
Transfer the stalks to a bowl, you can roughly mash using a mortal and pestle or use an immersion blender if you prefer it less chunky, add the lemon juice and process to a rough paste. Add the crushed garlic, tahini and salt, mix well and transfer to a plate.
Create a well in the middle of the dip, by using the back of the spoon. Add some olive oil to the well and serve with pita bread.