Prepare the leeks: Remove the tough green leaves about an inch above the white part of the leek stalk. Trim off the roots. Slice the leek lengthwise, then cut into half-moon pieces about ¼-inch thick. Fill a large bowl with cold water then add the cut up leeks, swishing them around with your hand a few times. Lift the leeks out of the bowl and place on your work surface. The gritty stuff will sink to the bottom of the bowl, the leeks should stay on the surface, easily separating the two. Discard the grit/dirty water. Repeat with fresh water until the water remaining is clear.

Heat up the oil in a large stockpot over moderately low heat. Add the garlic, prepared leeks, diced sweet peppers and celery, stirring to evenly coat everything. Occasionally stir the mixture, until the leeks begin to turn golden in color and the peppers become tender (30-40 minutes).

Add in the potatoes, thyme, turmeric, and at least enough broth to cover the potatoes by two inches. Add some salt and pepper, keeping in mind that you can always add more. Cook until the potatoes are completely cooked through (25-35 minutes).

Working in batches, blend the soup in a high-speed blender or in a food processor until smooth. Return the soup to the stock pot and bring the temperature back up to hot enough for serving.

Serve in bowls topped with sour cream or crème fraîche. Keep this vegan by topping with plain non-dairy yogurt. This soup both reheats and freezes well, so do with your leftovers whatever you wish!