In a bowl, mix the mayonnaise, minced garlic, and lemon juice. Set aside in the refrigerator.
Preheat the oven to 375 Degrees.
Place all Vegetables (Except lettuce or spinach) in a zip bag and drizzle vegetables with olive oil and shake bag until coated. Place vegetable pieces on a parchment lined cooking sheet. Cook for about 30 minutes. Remove to a plate and set aside.
Spread some of the mayonnaise mixture on the cut sides of the bread, and sprinkle each one with feta cheese. Place in a skillet set to medium high cheese side up, and cover with lid for 2 to 3 minutes. This will warm the bread, and slightly melt the cheese. Watch carefully so the bottoms don’t burn. Remove from skillet, and layer with the vegetables top with lettuce or spinach. Enjoy as open faced grilled sandwiches.