Step 1 Heat the oil in a large saucepan over medium-high heat, add the onions and cook, stirring, 2 minutes. Add the garlic, lower the heat to medium-low and continue cooking, covered, 10 minutes.
Step 2 While the onions and garlic cook, roast the corn in a dry skillet over high heat until slightly charred, turning so it does not burn, about 5 minutes. Cut the kernels from the cob and set aside.
Step 3Add the tomato paste and chipotle to the onions and cook over medium-high heat, stirring, 3 to 4 minutes. Add the vegetable broth and bring to boil. Simmer 5 minutes.
Step 4While the soup simmers, chop the avocado.
Step 5Puree the soup in a blender in small batches, returning each batch to the pan and combining well.
Step 6Divide the cheese, avocado, cilantro, corn and tortilla strips among 4 bowls and ladle the soup over the top.