What quantity of fresh herbs or spices should be used in place of dried and vice-versa?
In general, you can substitute one teaspoon of dried herbs for one tablespoon of fresh herbs and vice-versa (which is a one-to-three ratio). But let taste be your guide!
Dried - Dried herbs and spices are convenient and readily accessible for that last minute dish. Packaged dried herbs start out with a stronger aroma than fresh herbs, but will start to lose their pungency as they age. So if you've recently purchased a new jar or packet, you might want to use smaller amounts of dried herb at first until you know how strong the flavour is, or add a bit more as the herb becomes older. Most herbs in packets or jars will ultimately loose there flavour within 3 – 6 months depending how they are handled. After this time they have little or no flavour so lose their value in cooking.
Fresh - When possible, use fresh ingredients to gain the most flavour. They have a wonderful aroma and taste and add a colourful vibrancy to a dish. The only disadvantage is the herb can die within 3 days of purchase, they can also bruise easily, wilt or get cold burns. A great tip to extend their life is to pick them fresh and chop or rinse them when you get home. Then keep them in an airtight container which will increase their shelf life to about a week.
Making your own spice mixes - If you're grinding your own spices instead of using pre-ground, you might use a bit less than the recipe calls for, as fresh-ground spices are more flavorful than pre-ground.