When the summer ends, tomatoes are also in season. As basil is a perfect flavor match for tomato, fall is the perfect time to process up a freezer full of tomato soup, pasta sauce and pizza sauce.
In my mind, there's nothing better to stave off a winter chill that a bowl of good tomato soup and a grilled cheese sandwich. I've played around with my tomato soup recipe, and for freezing, it's best to avoid versions that involve large amounts of butter or cream or milk as the milk will separate and look curdled. Simple sauté a diced red onion, and four cloves of garlic until the onion goes translucent. Peel and seed two or three pounds of fresh tomatoes and toss them in along with a pinch of sugar. Simmer until the tomatoes cook down, then thin the mixture. Add a quart of stock (chicken, vegetable or beef) and salt and pepper to taste. Let cook for about half an hour, then sprinkle with chopped basil a minute or two before you take the soup off the heat. If you like your soup creamy, process in batches in a blender, or use an immersion blender. Add a spoon of yogurt or a splash of cream to each individual serving.
Pesto is the classic way of preserving basil (it's hard to dry without spoilage, and the leaves tend to turn unpleasant shades). The basil leaves are pureed with pine nuts and Parmesan or Romano cheese, using a steady stream of olive oil to keep the mass moving in the blender. You need more leaves for this process than you think, but the resulting paste is so strong you only need a spoonful to flavor most dishes. I like to freeze pesto in ice cube trays, then store the cubes in a freezer bag. That way, I can pop a cube out any time I need.
If you don't like pine nuts, substitute walnuts. If you want a more pure basil flavor, process the leaves just with the olive oil, then transfer the resulting paste to a clean glass jar and cover with half an inch of olive oil. You can keep the jar in the refrigerator for a couple of months.
Basil is a classic flavor of the Mediterranean, so add it fresh to dishes from this entire region.
Another cuisine that uses basil is Thai food. Thai basil (which has a slightly anise or licorice flavor) is used throughout Southeast Asia (particularly Vietnam.) Throw a few basil leaves into the bowl for a more flavorful and authentic pho noodle soup, but is best known for the role it plays in Thai curried noodle dishes. If you aren't growing Thai basil, you can substitute any of the more traditional basils without too much of a loss in flavor.
Citrus basils (such as lime and lemon) make a great addition to sauces for chicken pasta dishes, and are great sprinkled over fish before baking.
Basil can be infused into liquid, and then frozen into sorbet. It is a particularly good match with strawberries, peaches and limes. Just puree the fruits, add a bit of sugar and the basil liquid and freeze according to the ice cream machine's directions.
Basil flowers are not only pretty but edible and make a delicate addition to any salad.
Once you get started cooking with basil, you'll want to start collecting the different varieties for their intriguing flavor variations. After that, you won't be wondering what to do with all your basil, but what to substitute if you run out.