No, you do not necessarily have to start with oil first when cooking with a hot cast iron pan. While using oil is a common practice to prevent sticking and add flavor, there are other alternatives you can consider depending on your recipe and dietary preferences.
Dry heating: For some recipes, such as searing meats or toasting spices, you can start with a preheated dry cast iron pan. The high heat of the pan will create a sear or toast the spices without needing any oil.
Butter or other fats: Instead of oil, you can use butter or other fats like ghee or lard to cook in a cast iron pan. These fats can add rich flavor to your dishes.
Non-stick cooking spray: If you're concerned about using too much oil, you can use a non-stick cooking spray to lightly coat the pan before cooking.
Water test: Before adding any cooking fat, you can do a water test by sprinkling a few drops of water on the preheated pan. If the water beads up and dances around, the pan is ready to use. If the water evaporates instantly, the pan is not yet hot enough.
Oil after cooking: Alternatively, you can add oil towards the end of cooking or after the dish is cooked to enhance the flavor and provide a glossy finish.
Remember that cast iron pans are well-known for their non-stick properties when seasoned properly. Seasoning involves applying a layer of oil to the pan and heating it until it polymerizes into a slick surface. This seasoning can reduce the need for excessive oil when cooking.
Ultimately, the decision to use oil or not depends on your personal preferences, the recipe you're preparing, and your dietary choices.