Clean the dogfish and remove the head and fins with a sharp knife. Cut the dogfish into sections about 5cm long.
Place the dogfish in a large pan of salted water with the garlic, bay leaf, the peeled onion, salt and black pepper. Bring to the boil, reduce to a simmer and cook for 7-8 minutes. Remove from the heat, drain the dogfish with a skimmer, allow to cool for a while and then remove the skin which should peel away easily.
For the stew
Cut the potatoes in half, de-seed the pepper and cut into pieces. Peel and crush the garlic and halve the cherry tomatoes.
Heat a large saute pan over a medium heat, add 2 tbsp's of olive oil and when hot add the potatoes and toss to coat. Distribute evenly across the pan, and cook without stirring until browned on the bottom, 4-5 minutes. Turn and brown for 2-3 minutes more.
Stir in the peppers and garlic and cook stirring for 3 minutes. Add the tomatoes, tomato paste and 1 cup water. Reduce heat to medium-low, and bring to a simmer. Stir in the oregano, parsley and ¼ tsp salt.
Cover and simmer for 7 minutes until the potatoes are just tender. While the potatoes simmer, season the fish with ¼ tsp salt. Add the fish pieces to the pan along with remaining 3/4 cups water, pushing pieces down into liquid as best as possible (add a little more water to just cover fish, if necessary). Simmer gently until fish is cooked through, about 5 minutes, turning fish only once, if necessary.
To serve
Serve in bowls with crusty fresh bread to soak up the juices.