Place the tomatoes on a baking sheet, season with salt and pepper, sprinkle with the thyme sprigs and drizzle with 1 tablespoon of the oil. Roast in a preheated oven, 160°C (325°F), Gas Mark 3, for 1 hour until soft, then turn the oven up to 180°C (350°F), Gas Mark 4. Season the cod and roast along with the tomatoes in the oven for 10–12 minutes, or until the fish is cooked and the tomatoes have softened.
Brush both sides of the bread with the remaining oil. Preheat a griddle pan and griddle the bread until golden brown on both sides. Then rub both sides with the garlic clove.
Place the ingredients for the dressing in a small food processor and blend until smooth. You can also do this using a hand blender.
Top the toast with the tomatoes and then serve with the cod. Drizzle a little of the dressing over the top and garnish with some Parmesan shavings.