Preparation

Make the marinade

• Crush the lavender with a pinch of salt and then add it to the vinegar. Let steep for at least 5 hours. (The vinegar will keep in the fridge for weeks.)
• When ready to marinate, whisk the vinegar (no need to strain) with the olive oil, thyme, 1/2 tsp. salt, and 1/4 tsp. pepper.

Marinate the steak

• Reserve some of the marinade for basting, if you like, then use the rest to marinate the steaks for at least 30 minutes at room temperature and up to 8 hours refrigerated.
• If refrigerated, let the steaks come to room temperature before grilling. Pat the meat dry and season with additional salt and pepper.

Grill the steak

• For a charcoal grill, light a chimney starter full of charcoal and bank the coals against one side of the grill. For a gas grill, start with all burners on medium high and then turn off one or more of the burners.
• Grill the steaks over the hottest part of the grill, rotating them occasionally to create a crust, until well browned on one side, 2 to 4 minutes. Flip and sear the other side.
• Move the steak to the cooler part of the grill, cover, and cook, basting occasionally with the reserved marinade, to your desired doneness, about 8 to 12 minutes for medium rare. Let rest 5 to 10 minutes before serving.