1. Onions – white, red, yellow, sweet, whatever. Onions are an ingredient in a lot of recipes and can be sliced into a salad too. They add a lot of flavor and are normally not too expensive. Just keep in mind that not all onions have the same taste; red onions are sweeter than others.
2. Tomatoes – Like onions, tomatoes are used in many recipes. They can be baked, fried, put into a salsa — the options are endless. Often I will just dice it into my spaghetti and it makes me feel like I made a real effort to be healthy.
3. Limes – A lot of people are used to using lemons instead of limes, but I personally prefer using limes when cooking. You can use lime juice to smother steak and take away that “bloody” taste (unless you like it) or with fish and even chicken recipes. Limes are also really good for making your own salad dressings.
4. Lettuce – Lettuce is a staple in having a healthy diet. I like to always have lettuce so I can accompany whatever else I’m eating with a nice salad. There are of course many to choose from, but beware that some rot faster than others, and sometimes a veggie will look like lettuce but its not (this has happened to me).
Additionally, here is an article on the colors you should have on your plate every day. http://www.eatingwell.com/food_news_origins/seasonal_local/eatingwell_in_season/eating_well_by_color