Greg's beef udon noodle soup

Work in progress

This recipe comes from The Woks of Life. So far I have only sanitized it; I haven't cooked it yet.

Ingredients

For 2 servings

quantity	ingredient	step
1 l	water	1
	instant dashi powder (if not using prepared dashi stock)	1

15 ml	oil	2
200 g	onion (thinly sliced)	2
225 g	very thinly sliced beef (fatty beef chuck or ribeye for hot pot/shabu shabu)	2
5 g	sugar	2
15 ml	mirin	2
8 ml	soya sauce	2
5 ml	oyster sauce	2

400 g	fresh udon noodles (or 200 g dried udon noodles)	3
15 ml	mirin	3
8 ml	soya sauce	3
2	spring onions	3

Preparation

Prepare your dashi stock by bringing the water to a simmer in a medium pot and adding the dashi powder. Keep covered at a low simmer. If using prepared dashi stock, you may need to add salt to taste.
Heat the oil in a large frying pan over medium high heat, and cook the sliced onions for about 8 minutes, stirring often. Add the beef and sugar, and cook until the beef is slightly browned. Add 1 tablespoon mirin, ½ tablespoon soy sauce, the oyster sauce, and ½ cup of the dashi stock. Bring to a simmer, and cook for about 10 minutes to reduce the stock to a thin sauce.
Meanwhile, to the remaining dashi stock in the pot, add the remaining mirin and soya sauce. Add the noodles to the boiling water, and cook according to package instructions. Divide the noodles and dashi stock between the bowls. Top each bowl with half of the beef mixture and scallions. Serve immediately.

Notes

Even before trying to cook this, where does the sugar come from? US American influence? But at least it's not very much, if I have converted their units correctly. And it seems to me that the meat shouldn't be cooked that long.