The best way to know you're using the freshest ingredients is to cook with produce that's in season. Buying seasonal ingredients is also a great way to be a sustainable cook and eater! 

If you're like me and don't know what's in season where and when, then you might need a little extra help. Epicurious has a great interactive tool that shows you what's in season for your area at any given time. The site also gives great recipes and cooking tips to go along with each ingredient. 

April in New York is great for apples, onions, carrots, and potatoes. I know I'll be making this slice of heaven sometime soon...YUM!