Season the fish with salt and heat up the oil in a frying pan.
When the oil is hot, fry the fish until both sides are golden brown.
Remove the fish and drain the oil before setting the fish aside.
Pour 2 tablespoons of oil into a separate pan and saute garlic, ginger, and onion. Once they are sauteed, add the carrots and bell peppers.
Let the vegetables cook then pour in the vinegar and dissolved cornstarch. Stir it in then add sugar and ketchup. Season with salt and pepper and make sure the ingredients are fully mixed together.
Let the sauce simmer until it thickens and make sure to stir it so it doesn't stick to the pan.
When the sauce has reached the right consistency, pour it onto the fried fish and serve it fresh.