Cut the ends off of the zucchini and discard. Slice the zucchini into sticks about the size of your finger. Add the olive oil to a medium skillet over medium heat. When warm, add the zucchini. Toss to coat with the oil. Cover and cook for 10 to 12 minutes, turning once or twice, or until the zucchini is very soft when poked with a fork. Let cool slightly. Serve one piece at a time to your child if doing baby-led weaning. To make a puree, transfer to a blender. Blend smooth, adding the optional herb or spinach.