Don't waste your spices by using them on the wrong dishes. You need to understand how they work to get the most profit from using them This table shows information that will help you plan which spices to use on each dish.
If you add Super Salt to a dish, the amount of profit you gain depends on two things, the coins per serving (CPS) and the Servings (Srv) You want to pick a dish with a high coins per serving and high number of servings.
Here is a great tip. If a dish has 200 servings and you apply power pepper you will gain 20 servings giving 220 servings. If you apply again to the same dish you gain 22 servings. The third time you will gain 24 servings. This means it is better to keep applying to the same stove rather than spreading across stoves.