For dressing, whisk together first six ingredients. Place steak and 1/4 cup dressing in a resealable plastic bag; seal bag and turn to coat. Refrigerate 8 hours or overnight. Reserve remaining dressing; cover and refrigerate until serving., Drain beef, discarding marinade. Grill steak, covered, over medium heat or broil 4 in. from heat until meat reaches desired doneness (for medium-rare, a thermometer should read 135degrees; medium, 160degrees), 6-8 minutes per side. Let stand 5 minutes before slicing., To serve, divide salad greens among four plates. Top with steak, tomatoes, radishes and avocado; sprinkle with cranberries and, if desired, cheese and pepper. Serve with reserved dressing.