Combine sugar and water in a one-quart saucepan and place over medium-high heat. As soon as syrup comes to a full boil and sugar is completely dissolved, add the herbs and push them under the surface with a spoon and immediately remove pan from heat. Cover pan and let the herbs or flowers steep for 30 minutes. Pour syrup through a fine sieve and press down firmly on the herbs with the back of a spoon to extract any syrup held in the leaves. Store in a covered bottle or jar in the refrigerator for up to 3 months. Use as a base for poaching, flavoring drinks, brushing on cakes or as a syrup for fruit compotes.