Heat the oil in a 4-6-quart Dutch oven. Add the leeks and carrots and saute over low heat for 5 minutes without browning.
Stir in the red peppers and saute 3 minutes longer.
Add the potatoes, chicken stock, milk, bay leaf, thyme, and black pepper. Cover partially and simmer for 20 minutes, until the potatoes are tender but not falling apart.
Using a sharp knife and working from top to bottom, remove the corn kernels from the cob. Scrape off all the pulp.
Crush about 1/3 of the cooked vegetables and add the corn to the kettle. Simmer for 10 minutes.
Sprinkle parsley on top of each serving.