In a small bowl, add lime, onion, garlic, and salt. Slowly add oil, while stirring. Mix in the fresh herbs. Cover and let sit in the fridge for an hour or more. This will decrease the raw flavor of the onion and garlic.
In the mean time, combine the fresh corn, finely diced tomatoes, and cucumbers in a medium size bowl. When it is time to serve, add the dressing to the salad and gently stir to combine.