Cooking efficiently for PP restoration
Any cooked dish fully restores PP and temporarily powers up the move tied to its food category, so keep a stock of whichever dish matches the move you're about to lean on.
Eating a cooked dish does two things at once: it tops off your entire PP gauge and grants a temporary power-up to the Ditto move that food category is tied to. Salads boost Leafage (bigger grass and moss coverage), Bread boosts Cut, Hamburger Steaks boost Rock Smash and Rollout together, and Soups boost Water Gun. That means the smart approach isn't "cook one best dish" — it's keeping a few of each category stocked so you can eat the right one right before a big mining, chopping, or terraforming session.
Every dish is rated 1-5 stars depending on how it's cooked, and that star rating scales the power-up directly — a 5-star dish gives the full listed buff, while a 1-star version of the same recipe gives a much smaller, shorter-lived version of it. Simple Salad, Simple Bread, Simple Soup, and Simple Hamburger Steak are the earliest, cheapest options in each category and are enough to get the PP-restore-plus-buff loop going before better ingredients are available.
Food also comes in flavor categories (Spicy, Dry, Sweet, Bitter, Sour, and plain/No Flavor), and while your own PP restoration doesn't care about flavor, serving a Pokémon its preferred flavor gives a noticeably bigger Comfort Level boost than a random dish — so it's worth cooking with an eye toward both your own PP needs and whichever Pokémon you're about to feed.
Related: Simple Salad, Simple Bread, Simple Soup, Simple Hamburger Steak