1. First decide what you want to use for chopped clams and broth. If you are steaming clams check out 8 Things to Consider When Steaming Hard Shell Clams in the Techniques section. If you are using canned clams and bottled broth make sure that is on hand and we will proceed.
2. Saute the salt pork until crispy like bacon. Remove the salt pork to drain on paper towels and reserve, leaving the fat in the pot.
3. Add the onion, celery, white pepper and salt (if using) to the rendered fat and cook until translucent. Add the butter and stir until melted. Add just enough flour to absorb the fat and cook for a minute or two, stirring often. Regarding the amount of flour to use, we are not trying to thicken the chowder here but we do want to absorb the fat used to saute the vegetables so we don't have pools of liquid fat floating on top of our chowder.
4. Add the potatoes, clam juice and thyme bring to a light boil. Reduce heat, cover and simmer for about 20-25 minutes until the potatoes are cooked the way you like them.
5. Add the half and half and the clams and heat through, but do not bring to a boil. Test for seasoning and add if necessary.