Shuck the sweet corn, then wash the cobs and dry them thoroughly.
Turn the grill on to medium-high heat. Set the cobs on the grill and cook 8-10 minutes, turning frequently, until slightly charred. You can also use an indoor grill or a skillet over high heat to sear the cobs. (Use a skillet and stir frequently if you are working with pre-shucked corn.)
Slice the kernels away from the cob using a sharp knife. Transfer the kernels to a large bowl.
Add the chopped red onion, sliced tomato, radish slices, and minced jalapeño to the bowl with the corn kernels. Then add the feta and mix.
Zest the lime using a grater and add the lime zest to the bowl. Then slice the lime in half and squeeze the juice into the bowl as well.
Drizzle the olive oil over the salad and sprinkle in the cilantro. Then season with salt and smoked paprika. Stir well and taste -- adjust the level of seasoning to your preference.
Serve. This salad can be served immediately, or saved and served room temperature or cold.