Add red miso paste, chicken bouillon powder, water, and 1/4 cup flour to a saucepan. Whisk to combine.
Turn heat to medium low and whisk constantly, adding in arrowroot powder while you whisk to avoid clumps.
Slowly add more flour, 1/4 cup at a time, to your saucepan while whisking. Your gravy should start to thicken.
Then, add dashi stock and stir to combine. Continue to add flour while whisking until desired consistency is achieved, then remove from heat.
Serve immediately over your favorite meat or tofu.
Note: If you are preparing the gravy ahead of time, let cool before transferring into a glass container. Refrigerate for up to 5 days. When you re-heat your gravy, you may need to add a little water to thin it out.