This page of the trophy guide for Far Cry 6 explains how to unlock the Fry Cry trophy. You'll get it by purchasing 15 meals of your choice - from this page you'll learn how to order meals and what resources you need.
Buying meals is an activity associated with the main guerrilla hideouts in the game, i.e. those where the camera switches to the TPP view. These are Montero Farm from the Madrugada region, Patriotas Peak from the El Este region, and Camp Maximas from the Valle De Oro region.
You must start by going to the Construction Desk in a rebel camp and pay for the La Cantina blueprint. As the name suggests, it will add a cantina to the hideout and also unlock making meals.
Note - Only 2 blueprints can be purchased per hideout. If you have already chosen others before, just visit another hideout that still has free blueprint slots.
After unlocking the cantina, you can interact with it and view the list of available meals. It is quite modest at first, but upgrading the cantina to the next levels can expand it.
You can buy meals using meat from animals and fish. Unfortunately, you cannot pay for them with pesos.
You have to start fishing and hunting to get this trophy. You can go hunting in random places or discover hunting areas and fishing spots on the map.
Note - When hunting wild animals, remember to use a bow or crossbow if possible. This will reduce the risk of getting damaged meat, which can happen if it has taken too much bullet damage.
After you have unlocked the hideouts, look for a big cauldron in them (example in the picture). They have the same use and also allow you to get meals in exchange for the meat you are carrying.