Using a steamer or other steam equipment, steam potatoes until tender. Hold for later step.
In a steam-jacketed kettle or large stockpot, sauté vegetables until tender.
Add flour to vegetables. Stir with wire whip to combine. Cook for 5-10 minutes. Turn off heat.
Add water, base, and seasonings to roux, stirring constantly. Cook until mixture thickens.
Add steamed potatoes (from earlier step) and Roasted Red Peppers to onion, celery, and water mixture.
Heat to 185°F.
Add milk slowly to potato mixture. Stir constantly to combine. Heat to 180°F.
NOTE: Green, orange, or yellow bell peppers can be substituted for some or all of the red bell peppers.