You need to think of criteria that warrant inclusion of exclusion of a website from being a source for your research. When someone asks you "Why did (or didn't) you include this website", you need to be able to answer that satisfactorily.
The reason this is important, is so that you can show that you didn't just pick sources that suit your preexisting views and biases. You want to be able to show that you made a best effort to find all relevant cooking news website and filtered them by the criteria you set out at the start.
"it is a website that primarily focuses on news related to cooking".
That's a good first start. But what does it really mean?
- Does "about cooking" mean it's about recipes, or does it include cooking equipment, logistics, etc.
- Do you limit it to modern cooking, or is historic cooking included.
- Does "primary focus" mean that 50% or more of the pages on the site are about cooking? Or 70%? 30%?
- How will you measure it? Will you sample X pages, or analyze keywords on a full web-scrape of the website?
- How does the sort of research you wish to do affect the sources you can use? (If you need to scrape the source-websites, you should exclude ones that do not allow this, so that's an exclusion criterion.)
Try to think of all the criteria that might be relevant. The easiest way to start might be to collect some initial sources and look at them, so that you have an idea of the breadth of cooking-related websites. Then once you set your inclusion criteria, do another (broad) search and filter it down to your research set.