Whisk shallot, garlic, and herbs with oil in a baking dish just big enough to fit lamb in a single layer. Pat steaks dry, then turn in marinade to coat. Cover and chill at least 4 hours and up to 1 day, turning once or twice.
Take steaks out of refrigerator 1 hour before grilling.
Heat a grill to medium-high (450° to 500°). Pat off excess marinade with paper towels, then season generously with salt and pepper. Grill steaks, turning once, 10 to 12 minutes total for medium-rare (145° on an instant-read thermometer). Transfer each steak to a platter as done and add hunks of cheese. Let rest 5 minutes before serving. Top with chive, lavender, or thyme blossoms, if using.