Using a very sharp knife, slice the yellowtail into strips. Arrange the slices on a plate however you like, just make sure they’re in a single layer.
Combine lime juice, rice wine vinegar, soy sauce, sesame oil, and ginger paste in a small bowl. Whisk well, then set aside.
Pour the marinade over the top of the hamachi slices, then season everything with a generous pinch of flaky sea salt.
Garnish with thinly sliced radish, jalapeño slices, sesame seeds, and lots of fresh cilantro. Serve immediately!