Cut in 1 inches cubes all your vegetables, start by simmering them at medium heat without coloration, with the pancetta, butter, salt and pepper for about ten minutes.
Before you add the white wine, add the flour to make a small roux, that will help bring it all together later. Deglaze with wine and let it boil for 2 minutes. Pour the clam juice from the jar and add the milk. Let it simmer with a lid for another 10 minutes on low, make sure you stir occasionally.
I always put my clams when my potatoes are almost cooked and my sauce is glazing the spoon smoothly. Putting them too early can make the clams chewy. You can always finish you soup with a cloud of "crème fraîche".
