Udon can be eaten many ways; simmered in broth ("Nikomi" udon 煮込みうどん), in hot broth ("Kake" udon かけうどん), cold or hot with a dippin sauce ("Zaru" udon ざるうどん or "Kama-age" udon 釜揚げうどん), cooked in a small individual earthen pot ("Nabeyaki" udon 鍋焼きうどん) etc. Depending on the topping, it may be called differently such as Kitusne udon きつねうどん (with deep fried tofu pouch), Tanuki udon たぬきうどん (with bits of deep fried tempura without other items), "Tsukini" udon 月見うどん (with a raw egg), "Karei udond" カレーうどん(with curry sauce) etc.
The day I made this I had a leftover broth which was made with a dashi pack in the refrigerator. I added mirin, sake, and soy sauce to taste (I am not sure about the amount but I had about 3 cups of broth and I added 2 tbs each. And after tasting it I added more soy sauce).
For basic "kake" udon, only chopped scallion will be the topping but I added whatever I had. I had sake steamed (microwaved) chicken breast, frozen fish cake or chikuwa 竹輪, and "kyo-b(f)u" 京麩. "Fu" 麩 is made of 100% wheat gluten, so if you have gluten sensitive enteropathy, Celiac disease, or otherwise avoiding gluten, this is not for you. For that matter, udon noodle is not for you either. In any case, Kyoto is famous for decorative "fu" called "kyou-bu". It comes dried. I just dump these into the seasoned broth to just warm them up, hydrate or thawed and warm up. I also added chopped (on bias) scallion and Japanese 7 flavored red peper powder 七味唐辛子. Since I had a package of "ajitsuke nori" 味付け海苔 or seasoned nori, I also lined them up at the edge of the bowl. Just before eating, you can put it on the top. This is to prevent the nori to be totally soaked and soft before eating.
This was just OK. the broth was a bit too lightly seasoned. The kyou-bu was apparently too old and had a stale taste. The udon noodle and other items were just fine.