Finely chop the sage and rosemary leaves together.
Using a toothpick, prick holes about every 1 cm across the entire surface and length of the sausages. This allows excess fat to render out and helps the wine penetrate the meat.
Heat a drizzle of extra virgin olive oil in a skillet. Add the sausages and brown them thoroughly on all sides, which will take about 10 minutes.
Turn off the heat, wait a few seconds, then pour in the red wine and turn the flame back on. Let cook for an additional 15 minutes.
Using kitchen tongs, transfer the sausages to a serving dish and keep them warm. Continue simmering the sauce in the pan for another 5 minutes.
Add the chopped herbs and flour to the sauce. Whisk continuously until a smooth, thickened sauce forms, then strain it through a sieve. Pour the sauce over the plated sausages and serve.