Finely mince the garlic and ginger, then place them in a heatproof bowl. Add the chili oil, chili flakes (if using), salt, and white sesame seeds to the mixture. Stir it well to combine all the ingredients and set aside.

In a small pan, heat the granola or peanut oil over medium-high heat until it starts to smoke. This should take about 2-3 minutes. Carefully pour it over the garlic and ginger mixture.

After the oil is poured, stir in the soy sauce, dark rice vinegar, and sesame oil into the infused mix and mix thoroughly for about 30 seconds.

Bring a pot of salted water to a boil and add the udon noodles. Cook for 3-5 minutes until soft yet chewy. Drain and return to pot.

Add hot udon noodles to the bowl with the chili garlic sauce. Toss well for about a minute. Divide noodles among bowls and garnish as desired.