For The Most Flavorful Grilled Vegetable Sandwich, Marinate The Ingredients Overnight

Vegetables don't have to be relegated to boring house salads or measly side dishes. As plant-based eating is only growing in popularity throughout the U.S., the culinary spotlight is shifting, making fresh produce the star of the show. Now more than ever, chefs and foodies are finding creative ways to make veggie-forward dishes that don't just get the job done but truly dazzle. While some of these techniques require serious cooking chops, Mashed recipe developer Cecilia Ryu's secret to a stellar grilled vegetable sandwich is simple: overnight marination.

Thanks to the Maillard reaction, grilled vegetables always have a complex, caramelized flavor profile. Allowing them to spend the night luxuriating in a bath of oil, vinegar, and aromatics, however, is a surefire way to take your grilled veggie sandwich to the next level. Ryu's marinade uses the classic combination of olive oil, balsamic vinegar, minced garlic, salt, and pepper. "Balsamic vinegar has a sweet yet complex flavor," she told Mashed, adding, "The taste reminds me of a sweet fig, and it's not too sour."

Because meat is dense with connective tissue, marinades often can't deposit flavor deep within the cut. As such, they're mainly seasoning for the surface layer. Vegetables, on the other hand, are extremely fibrous, meaning they can easily absorb marinades. Ryu does point out that grilled vegetables can benefit from as little as 20 minutes of marination, though an overnight soak provides the most flavor.

For centuries, marinating has been used to flavor and preserve meat and seafood. As the technique improved over time, it became clear that soaking meat in a liquid mixture of fat, acid, herbs, and spices not only infused it with bolder flavor but also made it more tender, preemptively breaking down proteins and tissues before cooking. Vegetables also become softer the longer they marinate but for very different reasons.

One of the biggest mistakes you can make when grilling veggies is letting them marinate for too long. Via exosmosis, salt draws water out of vegetables, making them less firm. As such, over-marinating can make them mushy. To avoid this, try slicing your zucchini, summer squash, and peppers into larger, thicker pieces. Minimizing the exposed surface area makes it harder for salt to extract water, effectively extending the time your veggies can stay in the marinade. Reducing the amount of acid in the mixture can also keep fresh vegetables from breaking down and losing their structure.

With the right marinade, it's easy to make your vegetable sandwich shine. While Cecilia Ryu's vegetable marinade recipe has a distinctively Mediterranean vibe, you might also try different flavor combinations, like soy sauce, sriracha, and sesame oil or lemon, dill, and coconut oil.