Oishinbo-style, huh. Is this the first time we're seeing an original recipe from the manga?
That said, thanks for the TL.
I suppose it depends on what you consider an 'original recipe'.
Just a few chapters ago, Yamaoka unveiled his fried egg-don, which could be considered an Oishinbo original.
And every time we get an Ultimate Vs. Supreme showdown, Yamaoka will often put up an original recipe as well. One example off the top of my head is the brown sugar gyoza, which I don't think exists anywhere else.
If you're just looking for the direct mention of 'Oishinbo' in the name though, yes, this Oishinbo-style fish broth ramen would be the first.