Preheat the oven to 190°C/375°F and position one rack in the middle of the oven.

Place the quartered tomatoes, red bell pepper, and onions in a large baking dish.

Drizzle with olive oil, and sprinkle with salt, pepper, and garlic powder.

Toss to coat the vegetables evenly with the oil and spices.

Turn the tomatoes and bell pepper so that they are skin down in the dish.

Bake for about 45 minutes, or until the tomatoes start collapsing and the onions start caramelizing.

Empty the baking dish into a deep saucepan.

Puree the roasted vegetables with an immersion blender until smooth. If using a conventional blender, work in batches.

Blend in 250ml/1 cup of vegetable stock and continue adding stock about half a cup at a time until the soup reaches the desired consistency.

Stir in the sugar.

Add smoked paprika to taste.

Serve hot with croutons as a garnish.