On a clean, dry surface, use a Chef's knife to cut the corn kernels from the cobs. Then use the back of the knife, with a fair amount of pressure, scrape the cobs again to get all of the remaining bits of the kernels and their juices. Add the kernels and their juices to a bowl and set aside.
Place a double layer of paper towels on a plate and add the bacon to a large soup pot. Place the pot over medium-high heat and sauté the bacon until it's crisp, about 7 minutes. Transfer it to the paper towel-lined plate to drain. Crumble the bacon and set aside.
Add the onion to the pan with the bacon fat and cook over medium heat until golden brown, 7 minutes. Add the roasted yellow peppers, roasted jalapeño, ground Chipotle pepper, potatoes, tomatoes and corn kernels (along with their juices). Mix everything together and cook until the potatoes begin to brown, about 10 minutes.
Pour in the broth and bring to a boil. Reduce the heat to low, cover and simmer until the potatoes are tender, about 20 minutes.
Add the milk or cream and let it heat through.
Use an immersion blender to purée about half of the soup -- so it's both chunky and smooth.
Season to taste with salt and sugar.
Ladle the chowder into bowls and garnish with the bacon and avocado slices.