sauteed veggies in flatbrad, with a vinegrette dressing
grilled veggies on rye
steamed veggies on a hoagie
References :

Pita bread + falafel + fresh veggies (I like lettuce, alfalfa sprouts, tomato, and red onion.) + feta cheese + hummus or avocado spread.
You can buy a packaged falafel mix in the international section of most grocery stores. You usually just have to mix with with a few simple ingredients and then deep fry it. Cut the pita open (or in half for a smaller sandwich) and spread the sauce first, then stuff with everything else. It’s pretty simple and delicious.

You can also fry portobello mushrooms and eat them on a hamburger bun in place of the burger. This makes for a sandwich with a lot of substance. Add a little mayo (if you are cool with eggs), some swiss or muenster cheese, and tomato and lettuce.

Cucumbers are a vegetable that go great on sandwiches but are usually overlooked. I like to make a sandwich that ends up looking like a salad on bread.

You can also grill veggies and put them on a sub bun with like a teriyaki sauce and provolone cheese…

At Subway, I always get American cheese (because the kind they have at Subway is different and better than normal American cheese) lettuce, tomato, cucumbers, tomatoes, red onion, green peppers, banana peppers, and ranch dressing on Italian herb and cheese bread.

I hope it helps! Perhaps they aren’t the healthiest ideas, but I can assure you that they’re yummy!
References :

TLC:

Sesame seed bread, extra firm tofu, romaine lettuce, cucumber

method:
Wrap tofu snugly in 4 or 5 layers of paper towels and arrange on a plate. Cover with a second plate and balance a heavy can or two on top to weigh down the plate; set aside to drain for 20 minutes. Unwrap tofu and cut into 12 slices.

Preheat oven to 425°F. In a wide, shallow dish, whisk together liquid aminos, yeast, pimentón and 1 tablespoon water. Arrange tofu in dish, turn to coat well with marinade and set aside for 15 minutes. Spray a large baking sheet with cooking spray and arrange tofu slices about one inch apart in a single layer; spray all over with cooking spray.

Bake, flipping tofu halfway through, until firm and golden brown, about 30 minutes; set aside to let cool. Spread mayonnaise onto 4 bread slices, then top with lettuce, cucumbers, tofu and remaining bread and serve.

Eggplant sandwich:

French sandwich roll, sliced eggplant, tomato, onion, feta cheese,

method:
Preheat your oven’s broiler. Brush eggplant slices with olive oil, and place them on a baking sheet or broiling pan. Place the pan about 6 inches from the heat source. Cook under the broiler for 10 minutes, or until tender and toasted.

Split the French rolls lengthwise, and toast. In a cup or small bowl, stir together the mayonnaise and garlic. Spread this mixture on the toasted bread. Fill the rolls with eggplant slices, tomato, feta cheese and basil leaves.
References :

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References :
http://www.vegetariantutorial.blogspot.com