Adjust oven rack to lowest position and heat 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 some balsamic vinegar and olive oil. Toss in a few sprigs of thyme and/or rosemary, and sprinkle with salt and pepper.
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 even more golden. Serve hot, with crusty bread and butter.