To a large soup pot or Dutch oven, add the potatoes, onion, leeks, and celery. Pour the juice from the clams over the vegetables. Add water until the vegetables are completely covered; stir to combine. Bring to a boil, then turn heat to medium-low and simmer, stirring occasionally, for 10-15 minutes, or until vegetables are tender.
While the vegetables are cooking, melt the butter in a large saucepan over medium heat. Using a whisk, gradually blend the flour with the butter to make a roux. Gradually, about ¼ cup at a time, whisk in half & half. Let the mixture come to a slight bubble and continue cooking until it becomes thick and creamy (it will be quite thick).
When the vegetables are tender, add the thickened cream mixture to the large pot with the vegetables; stir to combine. Add the sea salt, sugar, and pepper; stir again to combine. Add the clams and stir well. Continue cooking until clams are heated through.
Serve hot with your choice of toppings.
Notes
Any kind of potatoes of your choice can be used.If you don’t have half & half on hand, use equal parts milk and cream to equal 1 quart. If you like bigger pieces of clam, use chopped clams instead of minced clams.The half & half mixture will thicken quickly once it starts to bubble, so stop cooking it once it becomes thick and no more lumps are remaining. If you want your chowder to be not as thick, add the half & half mixture to the pot of vegetables right before it starts to bubble and is still a little bit thin. Add the clams at the very end to avoid them becoming rubbery.