Heat a large pot on medium heat. Add the oil and onions and cook for 2 minutes. Combine the garlic, and ginger and cook for 2-3 minutes stirring constantly.
Add the miso paste, sesame seeds, sriracha, and soy sauce. Cook for 1 minute, stirring. Pour the broth and add your noodles. Cook for the time it takes for the noodles to be cooked. For the udon noodles it was 5 minutes. Pour in the milk and stir.
Divide into bowls and top with your favorite toppings.