Bring a large pot of water to a boil and cook the noodles as instructed on the package (about 5 minutes), until al dente. Drain well, rinse under lukewarm water, and set aside in a large bowl with 1 ½ teaspoon of sunflower in a warm place until later use.
Heat the remaining 2 tablespoons of sunflower oil in a large wok or frying pan over high heat. Add the green onions, garlic, ginger and chili peppers and cook, 2 to 3 minutes over high heat, stirring frequently, until the onions soften a little, without becoming too soft. Add the edamame and heat for about 30 seconds.
Quickly rinse the noodles under warm water if glued together and then, once drained, pour the contents of the wok over them, followed by sesame oil, sesame seeds, tamari, vinegar, cilantro and ⅓ teaspoon of salt. Mix well, sprinkle the lemon zest on top and serve immediately, with the slices next to it.
Placed in an airtight container, these soba noodles will keep in the refrigerator for 3 to 5 days.