"I don't know how to cook tuna with tomato."
Translation:Je ne sais pas cuisiner le thon à la tomate.
Because he is basically saying I do not know how to cook "all/any of this genre of recipes in the world(which is really only one.. maybe with some minor variations..remember not all the dishes but the 'genre' of dishes called tuna and tomato. If you had 'du' it would mean i know how to cook some tuna and tomato recipes and don't know how to cook others... which isn't really what is meant... he doesn't know how to cook any tuna and tomato recipe ...so the generalization with the article 'le'.
It is like when you use verbs such as hate /like. I hate carrots.. why you use the definite article..because you are basically saying i hate all carrots not thinking about the various varieties.. unless of course you specifically say so.
That is a great starting point. Here are some other guides. Savoir is used to mean to know a (veritable) fact... often followed by 'que' in those contexts . Savoir can never be used for a person.
a) Connaitre can ONLY be followed by a noun or pronoun(of course adjectives/possessives can qualify the nouns..like 'new PLACES; my MOTHER.. THIS ACTOR)..never a verb etc. b)Savoir is most often followed by a question word (why/how/where..etc = pourquoi;comment/ou) OR by a VERB in the infinitive/OR by NOTHING Je sais! but never Je connais!
In the limited cases that savoir is followed by a NOUN it is the NAME OF something you study or research..
And on top of it all when you are in real doubt....meaning it still does not easily fit the above categories...use connaitre because in those instances CONNAITRE is always right and savoir not.
Here' s an example from a DUOLINGO lesson of that final point: "I know a good recipe for peach pie" ... kinda confusing... is this a fact/a bit of knowledge/something I researched/knowledge of a thing... well you know what I am confused...but 'know' is followed by a noun/not by one of the 3 I mentioned for savoir nor by que and on top of that Connaitre is more often right when confused. So I am putting connaitre. And guess what..it is right but savoir wasn't.==Je connais une bonne recette de tarte aux pêches.