Rinse and dry peppers. In a large bowl, toss peppers with oil.
Heat a large skillet over medium-high heat for 2 minutes, until hot. Add peppers in a single layer and sprinkle with kosher salt.
Cook for 3-4 minutes, or until blistered and browned on one side. Flip and cook an additional 1-2 minutes*, until blistered on the other side. Alternatively, cook for 4-6 minutes, until blistered and browned, tossing occasionally.
Remove from heat. Squeeze lime juice over peppers if desired. Sprinkle with flaky sea salt and serve warm.
*For more firm peppers, remove from the heat once you see a few start to turn a lighter color.
Notes
Refrigerate leftovers in a covered container for up to 4 days.
Chop up leftover peppers and freeze in ice cube trays to use in sauces, soups or any recipe that needs a bit of color and flavor.