1. In a bowl, mix balsamic vinegar, olive oil, cumin, chipotle peppers, maple syrup, oregano, garlic, salt, and black pepper to make the marinade.
2. Submerge the flank steak in the marinade, ensuring it is well coated. Marinate in the refrigerator for at least 2 hours or overnight.
3. Preheat your grill to high heat. While the grill is heating, prepare the zucchini and brush each side with olive oil and sprinkle with salt.
4. Grill the marinated flank steak for 4 to 5 minutes on each side for medium-rare. Remove from the grill and let it rest for 5-10 minutes.
5. Grill the zucchini slices for about 2-3 minutes on each side until tender and slightly charred.
6. Prepare the chimichurri sauce by combining parsley, red wine vinegar, chili flakes, salt, and pepper in a bowl.
7. Slice the rested steak thinly against the grain and serve with grilled zucchini, whipped feta, and a drizzle of chimichurri sauce.
8. Garnish with optional fresh herbs and lemon wedges for added flavor.