1 cup firmly packed fresh flat-leaf parsley, trimmed of thick stems
3-4 garlic cloves
2 tablespoons fresh oregano leaves
1/2 cup olive oil
2 tablespoons red wine vinegar
1 teaspoon sea salt
1/4 teaspoon freshly ground black pepper
1/4 teaspoon red pepper flakes
2 lbs ground beef (85% lean makes a very juicy burger)
6 whole grain hamburger buns
6 slices smoked Gouda cheese
red onion, sliced into 6 thin, round pieces
salt
freshly ground black pepper