Rub the steaks with 1 tablespoon olive oil. Season both sides of the steaks with garlic powder, salt, black pepper, and thyme.
Let the steaks rest at room temperature for 15 minutes.
Place the zucchini, eggplant, and red bell pepper on a large plate. Drizzle the vegetables with 1 teaspoon olive oil. Season with salt and black pepper.
Heat a grill or grill pan over medium-high heat.
Place the vegetables on the hot grill. Grill the vegetables for 3 to 4 minutes per side, until tender and marked by the grill. Transfer the vegetables to a plate.
Heat 1 teaspoon olive oil in a small saucepan over medium heat.
Add the red onion. Cook the onion for 3 minutes, stirring often.
Add the cherry tomatoes, balsamic vinegar, brown sugar, salt, and black pepper. Cook the tomato mixture for 8 to 10 minutes, stirring often, until it thickens into a soft jam.
Place the steaks on the hot grill. Grill the steaks for 4 to 5 minutes per side for medium-rare, or continue cooking to your preferred doneness.
Transfer the steaks to a clean plate. Let the steaks rest for 5 minutes.
Divide the grilled vegetables among 4 plates. Place 1 steak over the vegetables on each plate.
Spoon the tomato onion jam around each steak. Drizzle each serving with balsamic glaze. Place a lettuce leaf behind each steak for garnish.
Notes
Tips and Tricks
Keep the vegetable slices thick - Slice the zucchini and eggplant about ½ inch thick to help them stay firm enough for the grill.Check the steak with a thermometer - An instant-read thermometer gives a more accurate result than cooking time alone because steak thickness can vary.Do not press the steak - Pressing the meat against the grill pushes out moisture.
Storing and Reheating
Refrigerate - Store the steak, grilled vegetables, and tomato onion jam in separate airtight containers for up to 3 days.Reheat on Stovetop - Place the steak in a covered skillet over low heat with 1 tablespoon water or broth. Warm until heated through.Reheat the Vegetables - Warm the vegetables in a skillet over medium-low heat until heated through.Warm the Tomato Onion Jam - Heat the jam in a small saucepan over low heat, stirring often.