Preheat oven to 230°C. Place the flour, eggs, milk, mustard and a pinch of salt in a food processor. Process until smooth. Season. Pour into a jug and set aside for 30 mins to rest.
Heat 1 tbsp of the olive oil in a large frying pan over medium heat. Cook the sausages, in batches, for 5 mins or until browned all over. Transfer to a plate.
Heat a 16cm x 26cm base measurement slab pan in the oven for 5 mins. Carefully pour in the vegetable oil. Heat the oil in oven for 2-3 mins. Carefully add sausages to the oil and pour over batter. Sprinkle with rosemary and 3 tsp of the thyme leaves. Bake in oven for 25-30 mins or until puffed and golden.
Meanwhile, heat the remaining 2 tsp olive oil in a medium saucepan over medium-low heat. Add the onion and cook, stirring, for 10 mins or until lightly caramelised. Add the gravy, ¼ cup (60ml) water, tomato chutney and remaining thyme leaves. Cook, stirring, for 5 mins or until heated through. Season.
Serve the toad-in-the-hole with the gravy and beans.