Heat the oil in a large skillet over medium-high heat.
Add the shallot, garlic, red pepper, green pepper, and red pepper flakes. Cook, stirring frequently, until the vegetables are softened, about 5 minutes.
Add the fish sauce, soy sauce, brown sugar, lime juice, and rice vinegar. Cook, stirring, until the sauce is thickened, about 2 minutes.
Add the noodles and cook, stirring frequently, until the noodles are heated through, about 5 minutes.
Stir in the peanuts and cilantro. Serve immediately.
Interesting Facts
Pad Thai noodles are a popular street food in Thailand.
The dish is believed to have originated in the 1930s.