The lentils in this recipe are important because they provide the moisture that helps keep these patties wet enough to shape into patties. You can use any variety (even canned), but just keep in mind that this could change the texture, taste, and consistency of the mixture. I've made this recipe countless times, and this is why I always boil brown lentils from scratch-- the lentils are the perfect texture and contain enough moisture to shape into firm patties.