Preheat grill, with lid closed, approximately 15 minutes or until temperature reaches 350° Fahrenheit.
While grill preheats, add 2 tablespoons sea salt to shallow bowl. Set aside.
Wash 4 medium russet potatoes under running water, using vegetable brush to remove all surface dirt. Pat potatoes completely dry with paper towels.
Place potatoes on cutting board. Very carefully, prick each potato with tines of fork, covering each potato in vent holes on all sides. Be careful not to push fork too far into potatoes.
After poking vent holes in each potato, cover potatoes with 4 tablespoons neutral-flavored oil (approximately 1 tablespoon per potato). Rub oil onto potatoes until all sides are coated completely.
Place one potato in bowl of salt. Roll potato in salt until all sides are coated, then transfer potato to microwave-safe plate. Repeat until all potatoes have been coated in salt, adding more salt to bowl as needed.
When all potatoes have been salted, place plate of potatoes in microwave. Microwave potatoes on 100% power 4 minutes.
Carefully remove potatoes from microwave. Wrap each potato securely in 2 sheets aluminum foil, covering potatoes completely.
Place foil-wrapped potatoes directly on grate in preheated grill. Grill potatoes, with grill lid closed, 30 minutes. Note: Time required will increase each time grill lid is opened.
After 30 minutes, open grill lid and very carefully unwrap one potato slightly. Insert fork or skewer into potato. If utensil does not pierce potato easily, rewrap potato and close grill lid. Grill potatoes 5 minutes more, then repeat process.
When fork or skewer pierces potatoes easily, with zero resistance, carefully remove potatoes from grill. Let potatoes cool 5 minutes.
After 5 minutes, unwrap potatoes and discard foil. Slice each potato open, cutting lengthwise down center of potato. Gently press ends of potato toward center of potato to widen cut, then fluff flesh inside potato with fork.
Top potatoes with sour cream, shredded cheddar cheese, sliced green onions, or other desired toppings. Serve immediately.