01 - Preheat an outdoor grill or grill pan over medium-high heat until it reaches approximately 400°F.
02 - In a small bowl, whisk together the olive oil, balsamic vinegar, minced garlic, dried oregano, dried thyme, sea salt, and black pepper until well combined.
03 - Brush both sides of each eggplant and tomato slice generously with the marinade using a basting brush. Allow the vegetables to rest for 10 minutes so the flavors penetrate.
04 - Place the eggplant slices directly on the grill grates. Cook for 4 to 5 minutes per side until fork-tender with distinct grill marks. Grill the red onion slices alongside if using.
05 - Arrange the tomato slices on the grill and cook for 2 to 3 minutes per side until lightly charred but still holding their shape. Avoid overcooking to prevent them from falling apart.
06 - Arrange the grilled eggplant, tomatoes, and red onion in layered stacks on a serving platter. Scatter torn fresh basil leaves over the top and sprinkle with crumbled feta cheese if desired.
07 - Present the dish warm or at room temperature. It pairs well with grilled crusty bread, couscous, or quinoa, and complements a crisp Sauvignon Blanc.