Place the pig's feet and ears into a large pot along with fennel, carrots, sage, tarragon, rosemary, onions, bay leaves, celery and lemons, and then cover ingredients with vegetable stock or water. Bring to a rolling boil and then immediately reduce the heat. Simmer for a minimum of 6 hours, testing for tenderness with a knife as you go. The ears will be cooked before the feet, so remove them sooner or add them to the pot later. When the flesh is tender, remove the pot from the heat and let it rest in the cooking liquid for 20 minutes.
Serve the cooked trotters and ears with a ladle-full of broth from the pot and some crispy French bread.