Cut the pancetta into strips about half an inch wide.
Heat a frying pan.
Spread the pancetta on the hot pan and allow to brown for a minute or so. Stir. Continue cooking until browned and fat has been rendered.
Add the vegetables one by one. Start with whatever takes longest to cook. If using raw corn, add it first. Otherwise, start with the carrot cubes. Sprinkle with salt and pepper. Stir fry for a minute. Add the next vegetable, and so on, until all the vegetables (except the scallions) are done. Remember to sprinkle salt and pepper after each addition.
Add the rice to the vegetables, mushrooms and pancetta. Sprinkle in more salt and pepper. Stir fry until heated through.
Off the heat, toss in the scallions.
Drizzle in the sesame oil and toss again.
Taste. Adjust the seasonings, if needed.