Heat the vegetable oil in a large skillet or wok over medium-high heat.

Crack the egg into the skillet and scramble it until it's cooked through.

Add the frozen peas and carrots to the skillet and stir-fry for 1-2 minutes until they're heated through.

Add the chilled rice to the skillet and stir-fry for 2-3 minutes, breaking up any clumps with a spatula or wooden spoon.

Add the soy sauce to the skillet and stir-fry for another minute until everything is well combined and heated through.