I mean, come on! Food is one of the best parts of worldbuilding!
Food in a culture is closely related to the flora and fauna located in the country. Whatever the locals can get their hands on is what ends up on their plates. Frog, horses, bugs, you name it. If your country is located near the sea, chances are they will eat a lot of fish and not very much other things like venison or rabbit.
Is there a hunting, foraging, or farming community in your story? Each one can overlap the others. Some hunters farm on the side and some foragers plant the seeds they find in the wild.
Let’s get real. Grocery stores don’t exist all around the world, but there are open air markets that have plenty of hand harvested food picked by locals. I suggest visiting an open air market to get a feel for it. I guarantee you’ll see things there that you’ll have no idea what to do with only to find out it’s a coconut in it’s natural form.
How things are cooked is another prized part of culture. Some things are cooked on a spit over a wood fire to give the food a smoky taste. If one of your cultures tends to be nomadic or happens to have a lot of open fires, then this is a key aspect to note.
Religion plays a very large part in food. Many cultures eat some animals to gain their properties and powers. Some have even eaten other people. Many animals are not consumed for respect or sacred reasons or because they are considered spiritually unfit for consumption. Some cultures consume animals and make sure to devour every single part of the animal and use everything else for various other needs.
Food is also a way to bring the family together. Many cultures have long periods of time where feasts are prepared for celebrations. It is the perfect time to bond and share stories, etc. The best way to make friends with locals is to have drinking games with their homemade alcohol.