This recipe for sweet corn soup combines so many of summer's best offerings - tender sweet corn, fresh savory herbs, bright flavor, and endless nostalgia. It's sweet but complex, and the herby gremolata perfectly compliments the fresh summer corn. You must use fresh corn - frozen is fine when corn isn't the star, but to get the flavor and texture just right here, use the freshest corn you can find.
Prepare the corn. Slice off one end of the cob so that you can hold it upright. Using a sharp knife, run the knife down the side of the cob to release the kernels. Set aside a small amount of fresh corn for garnish (a quarter to third of a cup).
Heat a dutch oven or other 6-quart pot over medium heat. Add butter and heat until it foams. Add onions, stir to coat in the fat, then cover. Sweat the onions over medium heat, stirring occasionally, until they are soft and translucent, 13-15 minutes.
Add the corn kernels, rosemary sprig, salt, pepper, and enough water to barely cover the vegetables (mine took just over 3 cups). Scrape any juices released onto the cutting board when slicing the corn as well. Place the cobs on top. It’s okay if the cobs aren’t completely submerged (they float).
Increase the heat to high and bring the liquid to a boil. Then, reduce to medium low and simmer for 10-12 minutes, until the corn is soft and the rosemary is wilted.
While the soup is simmering, prepare the gremolata. Finely chop the herbs and mince the basil. Place the herbs and basil in a small bowl and stir until incorporated.
Remove the soup from heat and fish out the corn cobs and rosemary sprig. Add the lime juice, then puree in the pot using an immersion blender. Taste for seasoning and add additional salt, pepper, or lime juice as needed.
Ladle the finished soup into bowls and garnish with a few splashes of olive oil and ½ - ¾ tbsp of gremolata. Serve immediately. This recipe doubles easily, and leftovers keep in a tightly sealed container in the fridge for up to a week, or frozen for up to three months.
Corn has a short shelf life, so use the freshest corn you can find - directly from a farmer is best, especially if it was picked that day.
There is absolutely no difference between white and yellow corn, so feel free to use whatever strikes your mood. I prefer yellow corn (or bi-color) simply for the color.
Take care to sweat, not sautee, the sweet onions. Too much caramelization will compete with the flavor of the corn.
Run the edge of a knife along the cobs to release some of the natural sugars and juice before tossing the cobs into the soup pot.
Don't skip the lime juice! The acidity balances the flavor and enhances the sweetness of the corn.