Mix all ingredients for the sour cream sauce together into a smooth cream. Set aside.
Sauté leek with oil and a pinch of salt for 3 min. Add champignons and keep sautéing until most of the liquid is evaporated. Add crumbled tofu, walnuts and lentils and stir well. Add some water and keep sautéing for a couple of minutes until all liquid is gone/evaporated. Season with pepper and let it cool down.
Take a piece of round shape dumpling wrapper, place some filling in the center. With a wet finger drop a bit of water over the whole round edge of wrapper dough, then fold the dough on half and stick together it's edges. Now fold the edge a couple of times on a couple of places by pressing the wrapper dough with a finger. Repeat this step with the rest wrappers.
Warm up a large non-stick frying pan, add oil and place dumplings in it. Let the dumplings fry for 1min.or 2 min. on high a temperature, then remove from the stove and add a little bit of water (just so it covers the bottom of pan). Cover the pan with a lid (or aluminium foil) and simmer over high temperature shortly until all liquid is gone. Let dumplings fry until golden in colour, then flip them and fry on the other side until golden brown colour. Serve warm dumplings with lots of toasted sesame seeds and with garlic sour cream sauce. Decorate with fresh basil, chili sauce and chili flakes.