1. Wash cucumbers, rub with coarse salt and let stand 20 to 30 minutes. Wipe dry. 2. Combine radish, table salt, sugar, red pepper powder, garlic, ginger and scallions. Cut cucumbers into two-inch chunks. Slit each piece down middle but not through end. Repeat at right angle to form cross. Fill with radish mixture. 3. Bring ¼ cup water to a boil, and pour into empty radish-mixing bowl. Swirl out, and pour water over cucumbers. 4. Place cucumbers in pan in single layer, sprinkle with sesame seeds, cover with plastic wrap and set aside. Serve when cool, or reserve for later use.