Though we all liked the taste -- and my husband and I definitely liked the added boost of nutrients -- I do recommend taking Lapine's suggestion to chill the patties first to make them firmer when you grill. I'll do that next time. Even cooked thoroughly, they're definitely much moister than your average burger, which can make them hard for little ones to eat. 

Barbell Burgers

Makes 4 burgers

Note: If time allows, make the burger patties ahead of time and chill them for an hour before grilling so they’re firmer and easier to handle.

¼ cup tomato paste

¼ cup Purple Puree (see recipe below)

¼ cup oat bran, plus more if needed

2 teaspoons Worcestershire sauce

½ teaspoon salt

1 pound lean ground beef

4 hamburger buns or English muffins, preferably whole-grain

Preheat an outdoor grill to medium-high, or heat an indoor grill pan to medium-high and spray with oil.

In a large bowl, mix tomato paste, Purple Puree, oat bran, Worcestershire sauce and salt. Add the ground beef, mixing with your hands until well combined. If the mixture is too sticky, add a bit more oat bran.

Using damp hands, shape mixture into four ¼-pound patties. (At this point, the burgers may be prepared a day ahead and kept covered in the refrigerator or frozen.)

Spray both sides of the burgers with oil and place them on the prepared grill. Cook for 4 to 7 minutes on each side, or to desired doneness. Serve on buns.

--From “The Sneaky Chef: How to Cheat on Your Man (In the Kitchen)” by Missy Chase Lapine

Per serving: 331 calories, 28 grams protein, 12 grams fat, 4 grams saturated fat, 32 grams carbohydrate, 5 grams fiber, 69 milligrams cholesterol, 225 milligrams sodium

Purple Puree

Makes about 1 cup puree

3 cups raw baby spinach leaves

1 ½ cups fresh or frozen blueberries, no syrup or sugar added

½ teaspoon lemon juice

1 to 2 tablespoons water

Thoroughly wash the spinach, even if the package says “prewashed.” If using frozen blueberries, quickly rinse them under cold water to thaw a little, and then drain.

Fill the bowl of your food processor or blender with the spinach, blueberries, lemon juice and 1 tablespoon water; puree on high until as smooth as possible. Stop occasionally to push the contents to the bottom. If necessary use another tablespoon of water to smooth out the puree.

Puree will keep in the refrigerator up to 3 days, or you can freeze ¼-cup portions in sealed plastic bags or small plastic containers.

Per 1/4 cup: 37 calories, 1 gram protein, 0 grams fat, 0 grams saturated fat, 9 grams carbohydrate, 2 grams fiber, 0 milligrams cholesterol, 18 milligrams sodium. Analysis by registered dietitian Jodie Shield.