Remove the jalapeño seeds if you prefer mild heat. If using fresh corn, shear off the corn kernels from 4 to 5 shucked ears of corn with a sharp knife over a bowl (you should have 2 to 2 1/2 cups). Using the back of a chef’s knife, scrape the sides of the cob to remove the pulp and add to the kernels. Add the cobs to the simmering stock and remove and discard (or compost) before blending. The soup can also be pureed with an immersion blender.