Use the blade of a knife to repeatedly "scrape" the fish skin from the tail to the head in order to remove any scales that might still be attached to the skin.
If your fish fillet(s) has a large bloodline, you can remove it in this step. This will also get rid of any remaining pin-bones. This step is optional and usually not necessary in fish with smaller fillets. Using a sharp knife, make a cut just above the center-line of the fillet.
Make a cut just below the center-line of the fillet. This will remove the center bloodline and any pin bones that may be present in this area of the fillet. Discard the bloodline.
Cut the fillet into roughly one-inch chunks. Season the flesh and skin side of the fillets well with salt and pepper. Set the fish aside for now. (I like to keep the belly flaps as this part of the fish is very moist and flavorful)
The garlic should be cut about 1/16th of an inch thick.
Put 1/3 cup olive oil into a large skillet. Heat it over medium-high heat.
When the oil starts to get hot, add the garlic and chili flake and cook while stirring.
Cook until the garlic is lightly brown and toasty. Do not let the garlic burn.
When the garlic is nice and toasty, add 2 pounds of halved cherry tomatoes. Season lightly with salt and pepper.
Turn the heat down to medium and cook the tomatoes until they start to soften and release their juices. You can press on the cherry tomatoes to help soften them up if necessary.
Once the tomatoes have softened up and released their juices, taste the "stew" and adjust the seasoning to taste with salt and pepper. If the tomatoes were not particularly sweet, you can also add sugar (to taste) to make up for any missing sweetness. Tear up some basil leaves and sprinkle them onto the potatoes.
After adding the basil, place the fish pieces into the pan as shown. Some pieces of fillet will be thicker. Make sure to press the thicker pieces into the tomato stew so that they cook evenly. It is also better to put the thicker pieces near the center of the pan, where they will be exposed to a bit more heat during the cooking process.
Keep the pan on medium heat, make sure the entire pan of tomatoes is simmering. Move the pan around on the flame if some parts of the tomato stew are not simmering. Once the whole pan is at a simmer, cover the pan tightly with a lid or aluminum foil. Let the fish cook for about 5-7 minutes while covered so that the tops of the fish fillets are cooked with the steam that is trapped in the pan.
Pick a large piece of fish and cut it in half to make sure that the fish is cooked and the skin has softened and is edible. If it needs more time, cover the pan back up and continue cooking until all of the fish is cooked. Sprinkle some more fresh basil leaves on top to garnish.
Plate some of the roasted potato/peppers/onion in a bowl and top with a few pieces of fish along with plenty of the stewed tomatoes and basil.