While meat lovers look forward to a Memorial Day barbecue, many people might be looking for a vegetarian option. With their high protein content, black beans lend meaty substance to veggie burgers. Too often, though, the patties turn to mush. So for this recipe from our book “Cook What You Have,” which draws on pantry staples to assemble easy, weeknight meals, we went looking for ways to improve their texture. The answer was three-fold. First, we only mash the beans coarsely so that when combined with other ingredients, we’re not left with a smooth paste. Second, we incorporate a significant...