Okay, inun-unan is a type of Filipino dish that is made by cooking fish in vinegar and spices. Imagine you are making a fish stew, but instead of using water to cook the fish, you use vinegar (the sour liquid that you sometimes use to make salad dressing).
First, you'll pick a type of fish you want to cook. Some popular choices are bangus (a type of milkfish), tilapia, or even tuna. Then you clean the fish by removing the scales and insides.
Next, you'll make a marinade by mixing vinegar, water, garlic (a type of seasoning), peppercorns (little black balls that make your food taste spicy), and salt. You'll place the fish in the marinade and let it sit for a little while (maybe an hour or two) so that the flavors soak into the fish.
After the fish has marinated, you'll cook it in the same marinade until it's all tender and easy to eat. The vinegar in the marinade makes the fish taste tangy and sour. Some people add more spices like ginger or onions to make it even tastier!
Finally, you can serve the inun-unan with white rice (yum!). This dish is popular in the Philippines because it's easy to cook and very delicious. So if you ever visit the Philippines, make sure to try inun-unan!