Heat the olive or coconut oil in a 2 qt (medium) sauce pan over medium heat until the oil shimmers. Add the shallots, ginger, and chili sauce, and saute until softened and fragrant (2-3 minutes). Add the broth, apple cider vinegar, and fish sauce/soy/tamari. Bring to a simmer, then reduce heat to medium low. Stir in the PB2 or peanut butter, sesame oil, and sugar, mixing well to combine. Finally, stir in the chopped peanuts.
for the noodle bowl
Prepare the soba noodles according to package directions, drain, and return them to the pot or to a roomy bowl. Pour half of the peanut sauce over the noodles and use tongs to turn the noodles, coating them with the sauce. Add more sauce until the noodles are satisfactorily covered in sauce.
Divide the noodles between two serving bowls and top with your favorite toppings.
Notes
*If your grocery store is anything like mine, you'll be confronted with several different types of "chili sauce" in the Asian/Thai section. If you already have a favorite (such as sriracha or Tobasco), go with it! My suggestion is to choose either the chili garlic sauce, which is hot, or the milder sweet chili sauce. Also, if you're a big fan of heat, don't hesitate to double or triple the quantity. My goal here was gently spicy, but do make it your own!