Scrub potato well and cut out any bad spots or eyes. Cube potato into 1 inch cubes.

Halve beans or leave whole, as desired.

Line base of pot with onions.

Wash fish and pat dry with paper towels. Lay the fish over the onions in the bottom of the pot. Sprinkle the top-side liberally with Cajun seasoning mix according to taste. Layer potatoes, garlic, onions, green beans and tomatoes, interspersing sprinkles of spices as desired. Pack in as many vegetables as possible keeping the lid tight.

Cover and bake for 35-45 minutes, or until fish flakes easily. You should smell the aroma wafting from the oven that tells you everything is done.

Tips
Any Cajun seasoning mix from the grocery will do, or mix together equal parts paprika, salt, and a dash of cayenne to make your own. Careful with the cayenne as a little goes a long way, especially in this "infusion cooking" method.

Use Cajun or Creole seasoning to bring that blackened taste to fish, seafood, poultry and meat, too.