Tomatoes
You can use them in everyday salads, make a quick sauce for pasta, or throw some in lentils or eggs. As for varieties, "roma" is my go-to, "cherry" requires less chopping, and "in the vine" tends to last longer.
Onions and/or bell pepper
Instant flavor every time for chicken, beef or beans. White and yellow onions are best for everyday cooking, red is very specific for certain recipes.
Lettuce of any kind
Make a quick salad, or a bed for chicken or beef. Put some in a sandwich and make it fancy! Substitute with raw spinach for increased nutrition, although it won't last very long in the fridge.
Eggs
They make great everyday breakfast, or you can make something special like quiche. If you bake cookies or cakes, you don't want to find yourself without.
Cheese
One day I will write a full poem about cheese. In the meantime, have some parmiggiano for pasta and soups. Have also a mild semisoft cheese, such as cheddar, gouda or mexican queso fresco, for salads and sandwiches.
Cold cuts
Let's be honest, one day you will not feel like cooking. But even if you make a simple sandwich or salad, you should be proud that you made it yourself and that it tastes fresh and delicious. Turkey is the leanest, ham and roast beef offer good variety.
Your favorite flavor
For me, it's lime juice. For some it's hot sauce. Some will not admit that their thing is ketchup. Whatever makes you more likely to eat something, keep plenty of it.
Two types of fruit
You know you are supposed to eat more fruit. You will be more likely to do it if you keep some at home. Choosing something seasonal is better for the earth and also for you. What is in season? If it’s on sale, most likely it’s in season.
Protein
OK, these are the specials of the week. Pick up to two entrees you will cook. Chicken, beef and pork fillets are easiest to cook.