Preheat your grill on medium high.
Place the corn directly onto the grill grates, with the husks still on. Grill over medium heat for 20-25 minutes, rotating as the husk begins to darken. Remove from the grill, carefully shuck, and set aside to cool.
Dice the tomatoes and cucumber. Chop the cilantro and green onion. Add those ingredients to a large mixing bowl.
Once cooled, cut the kernels from the corn cob and add the kernels to the other ingredients. Season with salt, pepper, the zest from half of the lime and the juice from the lime. You may not need all of the lime juice, so use your discretion.
Add the olive oil, stir to combine, taste and adjust seasonings if necessary. Serve at room temperature or chilled.