If using fresh lavender: Place the lavender flowers in a glass and use something like a cocktail muddler or mortar and pestle to crush the lavender. Stir in the lemon juice and simple syrup.
Strain out and discard the lavender flowers. Add ice and water to the liquid and serve with a sprig of fresh lavender and/or slice of lemon.
If using dried lavender: Boil the water. Place the dried lavender flowers in a mug and pour the boiling water over them. Let it steep for a few minutes, strain out and discard the lavender flowers and let the liquid cool completely. If using honey, stir it in before the liquid has cooled. Otherwise, once the liquid has cooled, stir in the lemon juice and simple syrup, add the ice and serve with a sprig of fresh lavender and/or slice of lemon.
This yields about one serving. For more servings simply double/quadruple the ingredients.