ingredientsus customary - metric 4-5 medium zucch sliced lengthwise into 1/8-inch slices (see notes) 1 tablespoon extra virgin olive oil 1 pound lean ground beef 1 medium yellow onion, finely diced 2 medium garlic cloves, minced 1 tablespoon thyme leaves, chopped 2 1/2 cups marinara sauce (see notes