Preheat the oven to 400 degrees(F).
Put the corn, jalapeno, onion and garlic on a large sheet pan.
Drizzle the vegetables with the olive oil and toss to coat everything evenly.
Sprinkle one teaspoon of the Tajin, the cumin, the chili powder, and salt over the vegetables. Toss again to coat everything in the spices.
Roast for 15 to 20 minutes or until the onions, jalapeno, and garlic are tender and the corn has started to brown.
Let the corn cool enough to handle it, then cut the kernels off the cob, letting them fall into a bowl.
Pour the corn kernels, jalapeno, onion, and garlic into a blender, as well as 1 cup of vegetable broth. Blend until smooth.
Pour the soup into a large pot and then heat it on medium-high. Add the remaining 2 cups of broth, vegan sour cream, vegan cheese, lime juice, and the remaining 1 teaspoon of Tajin. Stir until everything has melted together.
Turn the heat down to medium-low and let simmer for about 5 minutes. Taste and adjust the seasonings.
Serve with whatever toppings you want!