Prepare the pickled cucumber by combining the cucumber and 1/4 cup of seasoned rice vinegar in a small bowl; set aside.
Prepare the pickled red onion by combining the red onion with 2 tablespoons of rice vinegar in a small bowl; set aside.
Prepare the sriracha mayonnaise by combining the mayonnaise with the sriracha sauce in a small bowl; set aside.
Make the sauce by combining the soy sauce, sugar, minced garlic, and sesame oil in a small bowl; set aside.
Cook the beef in a large skillet over high heat until juices have evaporated, and it begins to fry in its own fat, 8-10 minutes.
Add the sauce mixture to the skillet and cook until nearly evaporated, about 2 minutes.
To serve the lettuce wraps, place the ground beef in a serving bowl and serve with lettuce wraps, cucumbers, red onion, radish slices, sriracha mayonnaise, and cilantro on the side.
This way, everyone can make theirs just the way they like it. Enjoy.