These veggie burgers draw their flavor from vegetables, and that's the way it should be.

The most foolproof here are the grilled portabella mushrooms, so it's no wonder Robin Donovan serves them up in "Campfire Cuisine." They're sturdy and so easy to prepare. Spray the caps with olive oil, shake on a little salt and pepper, and grill. They're ready in about 15 minutes. The rest of the recipes will require stovetop cooking because the delicate patties won't fare well on the grill. Flip them carefully, or they're fall apart.

While fragile in structure, they're big on flavor and plenty accommodating when it comes to swapping ingredients.

Make them with any vegetable or beans on hand that can be mashed: black, white or red beans, chickpeas, lentils or potatoes. Swap the vegetables: beets for carrots, or try parsnips or sweet potatoes. Change up the binders: Use quick cook oats, bread crumbs, unseasoned cornmeal stuffing.

Grilled Portabella Burgers

Serves: 4

• 4 large portabella mushrooms, stems trimmed

• Olive oil spray

• Salt and pepper

• 4 hamburger buns, toasted

• 1/2 cup jarred roasted red bell peppers

Spray the mushrooms all over with olive oil or cooking spray. Season with salt and pepper to taste. Grill over medium-high heat for 7 to 8 minutes per side, until tender. Serve on toasted buns, topped with roasted peppers and any other desired garnishes.

From "Campfire Cuisine: Gourmet Recipes for the Great Outdoors" by Robin Donovan (Quirk Books, $15.95).

Vegan Burgers

Serves: 4

• 2 cups cooked or canned black, white or red beans, chickpeas or lentils, drained, liquid reserved

• 1 small onion, chopped

• 1 tablespoon garlic, chopped

• 1/2 cup rolled oats

• 4 carrots, peeled and grated (1 1/2 cups)

• 1/4 cup chopped fresh parsley or cilantro

• 1 tablespoon chili powder or other spice mix

• 1 teaspoon salt

• Black pepper to taste

• 1/4 cup olive oil

• 8 slices whole wheat toast or buns

• 4 lettuce leaves, sliced whole tomato, sliced half red onion

• 4 tablespoons mustard

Combine beans, onion, garlic, oats, carrots, parsley, chili powder, salt and pepper in a food processor. Pulse until combined but not puréed. If the mixture does not hold together, add reserved bean liquid a tablespoon at a time until it does. Let the mixture rest for a few minutes before shaping burgers.

Shape into patties 1 inch thick. Cover and refrigerate for several hours. Film the bottom of a large nonstick or cast-iron skillet with the oil and turn the heat to medium. Cook patties in the hot skillet, 3 to 5 minutes per side.

From "VB6: Eat Vegan Before 6:00 to Lose Weight and Restore Your Health - for Good" by Mark Bittman (Clarkson Potter, $26).

Mushroom Burgers

Serves: 4

• 2/3 cup water

• 1/3 cup cooked red or brown rice or quinoa

• 1 pound portabella mushrooms, stems discarded

• 1 cup finely chopped onion

• 1 cup finely chopped red bell pepper

• 3 tablespoon unsalted butter

• 2 garlic cloves, finely chopped

• 3/4 teaspoon salt

• 1/2 teaspoon pepper

• 3 tablespoons chopped fresh flat-leaf parsley

• 1 teaspoon soy sauce

• 1/2 cup fine dry bread crumbs

• 1 large egg, slightly beaten

• 1/4 cup olive oil

Break one-third of mushrooms into a food processor and pulse until finely chopped, then transfer to a bowl. Repeat with the remaining two batches.

Cook onion and bell pepper in the butter in a 12-inch heavy skillet over medium heat, stirring occasionally until softened, about 5 minutes. Add the chopped mushrooms, garlic, 3/4 teaspoon salt and 1/2 teaspoon pepper and cook over medium-high heat, stirring occasionally until any liquid the mushrooms give off is evaporated and the mushrooms begin to brown, 8 to 10 minutes.

Transfer mixture to a large bowl and stir in the rice, parsley, soy sauce and 1/2 cup bread crumbs. Cool 10 minutes. Stir in egg. Form patties and chill 1 hour.

Heat oil in a 12-inch heavy skillet over medium-high heat. Fry patties until deep golden brown, turning over once, about 4 minutes total or until cooked through.

Adapted from "The Epicurious Cookbook" by Tanya Steel and the editors of (Clarkson Potter, $27.99).