Preheat oven to 425 degrees
Toss corn with oil & place on a sheet pan
Roast until kernels have browned, approximately 10 minutes, stirring occasionally
Heat margarine, sauté garlic for one minute
Add onions, carrots, celery, chipotle powder, ancho powder, cumin and white pepper, cook for 2 minutes
Add flour to create roux, cook for 5 minutes
Stirring constantly with wire whisk, add water and chicken base. Bring to boil, reduce heat and simmer for 20 minutes
Add roasted corn, simmer for 15 minutes
Add the half & half and simmer 5 more minutes, season with salt
Serve with tomatoes, scallion & cilantro as a garnish