Toss the heirloom tomatoes, red onion and cilantro in a small bowl. Season with salt and pepper to taste and set aside.
Preheat a grill. Lightly coat the ears of corn with vegetable oil. Grill the corn, turning frequently until the majority of the kernels are brown. Remove the kernels from the cob, cutting close to the cob so as to remove as much of the starch in the cob as possible.
In a large pot, saute the onion and bacon until the bacon is crisp. Add cumin and cook for another couple of minutes. Add the corn, water, and chipotle. Simmer for 1 hour. Using a hand blender, puree on high speed until smooth. Add lime juice and season with salt. Strain through a fine strainer.
Divide soup into 4 bowls and spoon the heirloom salsa in the center. Break apart the filet of trout and place over the salsa. Garnish with a fresh sprig of cilantro.