First, wash the pompano thoroughly, inside and out, and pat it dry. You can cut it into halves if you'd like. Then, season it with salt and pepper to taste.

In a wide pan over medium heat, heat up some oil. Once it's hot, add onions, garlic, and ginger. Keep stirring them until they become soft and fragrant.

Next, add tomatoes and mash them with the back of a spoon. Cook until they begin to soften and release their juices.

Then, add fish sauce and cook for about a minute, stirring occasionally.

Now, it's time to add water and bring it to a boil. Cook for 2 to 3 minutes or until the tomatoes have completely softened. Add tamarind powder and stir until it's dissolved.

Add the fish in a single layer, lower the heat, and cover. Continue to cook for about 10 to 15 minutes or until the fish is cooked through and the liquid is reduced.

Lastly, season with salt and pepper to taste. Serve hot and enjoy your delicious pompano dish!