Steps
1. Preheat a grill pan over medium heat.
2. Toss zucchini, red bell pepper, and eggplant slices with olive oil, salt, and pepper.
3. Grill the vegetables for about 3-4 minutes on each side until tender and slightly charred.
4. In a small bowl, mix mayonnaise, lemon juice, and chopped basil leaves to create basil mayo.
5. Toast the bread slices until golden brown.
6. Spread the basil mayo evenly on one side of each bread slice.
7. Layer the grilled vegetables onto one bread slice and sprinkle crumbled feta cheese on top.
8. Close the sandwich with the other bread slice, cut in half, and serve immediately.