Heat grill pan or large skillet on high and lightly coat with olive oil. Add steak to pan and cook to desired doneness, 2-4 minutes per side for medium rare. Let stand 5 minutes and cut against the grain into thin slices. You can also grill this on an outdoor grill if you have one.
Make dressing by combining orange juice, olive olive, sesame oil, garlic, and fresh cilantro in a food processor or blender and blend until combined.
While steak rests, toss vegetables and mixed greens with enough dressing to coat, you may not need to use all the dressing. Slice steak against the grain. Top salad with steak and serve.