In a large microwavable bowl, whisk together the cornmeal, water and salt. Cook on high for 5 minutes. Stir, and then microwave on high for an additional 2 minutes. Remove the polenta from the microwave and let it rest for 1 minute. The polenta should be the consistency of pudding. If it appears watery, microwave for an additional 1-2 minutes. Remove from the microwave, stir in the oil, and enjoy!