Place the cucumbers into a bowl and scatter over the salt. Massage the salt into the cucumber and leave for 5 minutes.
Heat a large frying pan (skillet) on medium high heat for 2 minutes. Drizzle with 1 to 2 tablespoons oil and add the potsticker dumplings, flat side down, and cook until the bottoms of the dumplings are lightly browned, 1 to 2 minutes (depending upon the size of your pan, you may need to cook in batches). Immediately add about ¼ cup of water to the pan, just enough to cover the base of the dumplings, then cover and cook until the water has evaporated, 3 to 4 minutes. Transfer to a plate. Continue cooking the remaining dumplings.
Meanwhile, in a large bowl, make the sauce: add the vinegar, soy sauce or tamari, sesame oil and sugar and whisk well, until the sugar dissolved.
Squeeze the cucumber to expel as much water as possible. Add the cucumber to the dressing, along with the avocado, scallions and dumplings. Toss gently to combine.
Serve immediately, topped with sesame seeds.
Notes
Want it spicy? Finish with a few sliced chilies or a few drops of chili crisp.