People who are serious about their food often talk about the concept of seasonal eating. In other words, having a diet that revolves around what is in season at the time. The benefits of this are that you are theoretically getting your fruits and vegetables when they are at their freshest, cheapest, tastiest and most nutritious. By default you are more likely to be eating local produce as well, as out-of-season produce is brought in from greater distances involving greater fuel consumption. Thus it is a more environmentally sustainable way to live.
The key has been growing my own vegetables. Since buying my own place I've developed an interest in this, but it has gradually turned into a full-blown obsession. Yes, I'm aware that such a pastime is not especially edgy or cool, but for some reason I like listening to gangsta rap while gardening, which I figure makes me pretty badass.
So Summer has just finished, and I still enjoyed substantial crops of tomatoes, eggplant, cucumber, capsicum, strawberries, zucchini and green beans, while I'm experimenting somewhat successfully with okra, bitter gourd and sweet potato. Likewise, in the Spring I grew so many broad beans and ate so many of them that I ended up having to freeze a couple of bags lest I risk never wanting to eat broad beans again.
Having such plentiful vegetables means that you have to make the most of it. It's effectively free, after all (the monetary outlay having come much earlier) and there is undoubtedly a feeling of smug satisfaction knowing that you can create your own food. Since I don't have any kids yet, agricultural pursuits will have to fill that nurturing void in my life, being another way of raising something from my own seed, if you will.
As an avid foodie I am capable of cooking things from a wide variety of cuisines, but seasonality means that certain cuisines take precedence at different times of the year. There are certain things you can only grow in Summer and early Autumn - tomatoes, cucurbits (cucumber, zucchini and the like), basil - so I draw from culinary traditions that make the most out of them. So that means the Mediterranean diet goes into overload. Greek, Italian, Turkish, Spanish, Provencal. Mexican too. Since I grow Thai basil and the lemon basil (kemangi) which we use in Indonesia, those cuisines get a good look-in as well.
But in Winter there aren't so many options. It's great for various green leafy things - spinach, edible chrysanthemum, snowpea leaf tips, various brassicas (the cabbage family) of both the European and Asian varieties. Which means that I start cooking Chinese and Korean food a bit more often. But in general there is less bounty, so it's a time in which I am forced to rely less on fresh pickings and more on the staples of the cupboard, such as dried peas and lentils, and tinned tomatoes. Thus the focus also shifts to Indian and Middle-Eastern stews and curries. The cooler months are also the bumper season for citrus; this combined with the profusion of leafy greens means that the Greek staple horta (cooked greens with lemon and olive oil).
Obviously there are themes developing here but I don't stick to them religiously by any means... I buy plenty of things out of season because I want to eat them. But it's more about making the most of what's available. You'll notice that I tend slightly towards Southern European foods in Summer and Asian foods in Winter. That is largely because Western food has a fairly simple approach to spices, and puts more emphasis on the taste of the vegetables themselves. Therefore you need to have good, fresh produce, and Summer is the prime time for this. Asian foods have a more complex approach to seasoning, which means that it is less imperative for the absolute best quality ingredients.
Of course, one of the perks of living in the modern world is that I can enjoy food that has been flown in from another continent to meet my particular needs. Whatever the ecological drawbacks of this, it at least means I don't have to just eat cabbage all winter. But now that I've learned to co-exist a little more with the seasons, there's certainly a certain intangible benefit to be gained, even if it's only a sense of smug self-satisfaction.