Preheat grill to medium-high heat. Remove husks and silks from corn. Rub the corn and the green onions with olive oil and sprinkle with salt. Place corn and green onions on the hottest part of the grill and cook until lightly charred on all sides. The green onions will take about 3-5 minutes total and the corn about 7-10 minutes. Remove from the grill and allow to cool enough to touch.
Using a sharp knife and standing the corn cobs up on end, cut the kernels off of each cob into a bowl. Chop the green onions and add to the bowl with the corn. Add the basil and toss to combine.
Whisk together all dressing ingredients. Drizzle over the corn, green onion and basil, tossing to coat (you may have dressing left over). Top with crumbled bacon and feta and serve at room temperature.