Instructions

1. Make the marinade. Mix oil and and an acidic liquid at a ratio of about 2/3 cup oil to 1/3 cup acidic liquid for every 1.5 pounds of fish. Flavor it with additional seasonings and sauces, like soy or Worcestershire, to taste. Whisk all the ingredients together.

2. Pour the marinade in a shallow glass baking dish and set the fish fillets inside. Turn the fillets over a few times to help them better absorb the marinade.

3. Place the marinating fish in the refrigerator for 20 minutes to 3 hours.

4. Preheat your oven to 375 degrees Fahrenheit.

5. Assemble aluminum foil rectangles. For each piece of fish, use a rectangle that is about 12 inches wide and 20 inches long. Fold the first aluminum foil sheet in half width-wise to form a crease, then lay it flat once more.

6. Brush the foil on either side of the crease with oil, leaving the outer edge of the rectangle free of oil.

7. Set a single fish fillet in the center of one half of the rectangle and fold the second half of foil at the crease, over the fish. Crease the edges together on the three open sides to create a sealed packet around the fish.

8. Repeat with the remaining fillets and aluminum foil rectangles.

9. Put fish packets on baking sheets, two packets per sheet. Set the sheets in the oven and bake for about 15 minutes, rotating the baking sheets midway through the cooking time.

10. Make a small slit in one of the packets and insert the cooking thermometer into one of the fillets. If it registers at least 145 degrees Fahrenheit, take the baking sheets out of the oven.

11. Set a foil packet on individual plates to serve. Alternatively, open each packet, remove the cooked fish, and set all of the fillets on a serving platter.