I think using flaxseed oil is the best approach for cast iron seasoning. You want to heat the pan slowly so it warms evenly, then wipe a very thin coat of oil all over the surface. After that you place it upside down in the oven at around 450 degrees for about an hour. Let it cool completely inside the oven before repeating. Three rounds of this should give you a nice dark surface that works well for eggs and other delicate foods. Just make sure you are using enough oil but not too much because it can get sticky if you overdo it. The key is thin layers and patience between each round. I have been doing this for years and it always works well for me. You can also use grapeseed oil if flaxseed is hard to find and it produces similar results. The oven temperature matters a lot so use an oven thermometer to be sure it is accurate.

I think a cold pasta salad would be a great choice for the potluck. You can make it the night before with cherry tomatoes, fresh basil, mozzarella pearls, and a simple vinaigrette. It actually tastes better after sitting overnight because the flavors blend together. Just keep it in the fridge and toss it gently before serving. Another option is a grain bowl with roasted vegetables and a lemon dressing. Both of these travel easily and do not need to be reheated. People tend to gravitate toward things that are familiar but with a little twist. I would stay away from anything with mayonnaise if it is going to sit out for a while. Let me know if you want me to bring something specific instead. I am happy to coordinate with everyone so we do not end up with too many similar dishes.