Let the steak sit at room temperature for 30 minutes.
Pat dry the steak with paper towel. Sprinkle both sides (and the edges) generously with kosher salt and freshly ground black pepper.
Heat the olive oil in a cast iron pan on high heat. I usually use a silicone brush to apply the oil. Sear the steak in the pan, about 3-4 minute each side. During this time, do not move the steak around or flip. You can use tongs to press down so the steak gets nice sear marks.
Remove the steak from the heat and let it rest on a cutting board for 10 minutes. If you cut the meat right away, all the juice will come out. Cut thin slices, against the grain of the meat.
Prepare Shoyu dressing:
In a food processor, puree the onion.
In a 1-cup measuring cup, add soy sauce, pureed onion, and olive oil.
Add mirin, and sugar, and rice vinegar.
Add lemon juice and sesame seeds and whisk all together.
Assemble the salad:
Assemble the salad with Asian greens (baby kale, Asian greens, baby spinach), water melon radish, red radishes, English cucumber, avocado, and cherry tomatoes. You can choose any leafy salad and other salad ingredients you like.
Place the steak on top and drizzle the shoyu dressing.