Everything you should have in the fridge, freezer, cupboard, and spice rack.
In the Fridge
These items keep well and are versatile enough to augment most recipes: Unsalted butter, lemons, limes, shallots, carrots, celery, parsnips, ginger root (grated directly over a dish, it makes everything but a cupcake better), Parmigiano (buy a wedge of imported Reggiano—hopelessly expensive, but anything else is what margarine is to butter), plain yogurt (as a base for salad dressings and pan sauces; should be used instead of sour cream and, in a pinch, buttermilk), large eggs, green and black olives (sauté with onions, add a bay leaf or two and some fresh or dry marjoram, plus stock and white wine, and let reduce for a quick and dirty sauce for chicken or pork. Replace chicken stock with vegetable stock for fish).
In addition to two more bars of unsalted butter, store the following in individual packaged ziplock bags, marked with the date of arrival: Roll of polenta, bacon or pancetta, ravioli or tortellini, loaf of brioche (whole), peasant bread (sliced).
For all the prattle about fresh, there are a few canned and packaged essentials: Crushed tomatoes; chicken, beef, and vegetable stock; canned beans; cornmeal; all-purpose four; Wondra (instant flour, good for coating fish); dry pasta; garlic; pine nuts; walnuts; sweet potatoes.
My rule of thumb is, if you can’t remember why you bought a seasoning, throw it away immediately. (Goodbye fenugreek.) And whenever possible buy spices whole and ground: Bay leaves, oregano, rosemary, sage, savory, thyme, allspice, Chinese five-spice powder (versatile mix that offers all that’s good on the palate: sweet, sour, bitter, pungent, and salty), peppercorns, staranise (this complements pork and chicken), cinnamon, cloves, coriander, cumin, nutmeg (not just for baking: Great whole nutmeg over beef roasts and french toast), curry powder, chile powder, fennel seeds (add to sautéed vegetables and poached fish), ginger powder (also good for sautéed vegetables), mustard powder (key for salad dressings), paprika, cayenne powder.