Dried herbs have more intensity, stronger smell and bitter taste in comparison to fresh herbs. This is because, in dried herbs, the volatile oils are in concentrated form. Herbs such as oregano, thyme, rosemary in dried form gives a good flavor.
If a recipe calls for 1 Tbsp of chopped fresh herbs, it can be substituted with 1 Tsp of dried herbs using the ratio of 3:1. Crush it with fingers and add it at the start of the cooking while sautéing with oil/butter. We used this approach for cooking mint tomato sauce penne pasta using dried mint leaves. This is done because dried herbs needs longer time to infuse the flavor in the dish.
Fresh herbs release flavor quickly and are added at the end of the cooking as a garnish where they retain their freshness and color. Certain herbs- curry leaves, dill, parsley, cilantro and chives are best when used fresh. Dill leaves does well as garnish and can also be made into a side dish as we did in cooking Dill leaves with lentils.
It is best to add curry leaves while tempering than add it as a garnish to release its flavor. Tempering can be done at the start like how we did with chicken curry or at the end of the cooking like in fish masala curry. Dried curry leaves have less aroma and pungency than fresh curry leaves so would be required in double the quantity when used in a recipe.
If you are using herbs during marination, use dried herbs as fresh herbs leaches out moisture in the presence of salt.
Dried herbs lack longer shelf life, lose its flavor quickly and give an off taste when added to the recipe. It is advised to throw off old bottles of dried herbs. Do note that bay leaf is not a herb but a spice and dried bay leaf can be stored for almost two years.