Preheat the oven to 425°F.
Scatter the tomatoes over the bottom of a baking dish.
Add the garlic, lay the sausages overtop, and drizzle it all with oil and balsamic vinegar.
Toss in the rosemary and sprinkle with salt and pepper. Bake for about 20 minutes.
When the tomatoes have split and the sausages are golden, remove the dish from the oven and stir in the beans.
Return to the oven for 20 minutes or so, until the beans are cooked through and the sausages are cooked through.
Serve hot, with crusty bread and butter.