Translation:We are going to demonstrate that we can cook.
Sorry it's not about the accent. Question words like cuándo, qué, and dónde use accents when they're used as a question, otherwise the accent is absent. It's actually about the missing direct object "lo" which together with "que" as "lo que" should mean "what" as in "this is what I do" (esto es
lo que hago).
Maybe I'm over-thinking this, but should Saber rather than Poder be used in this context? As far as my knowledge stretches: Poder shows that someone can do something in the sense that they are available to do it by having time or materials Saber is used to demonstrate that they know how to do something by possessing the relevant skills.