Slice the sausages in 3. In a large skillet, heat olive oil.
Cook the sausages slices and onion for 2 minutes. Add rice, mix well and cook 1 minute. Deglaze with beer and bring to a boil.
Transfer everything in the slow cooker and add remaining ingredients except peas and carrots. Cook on low for 6 hours. 30 minutes before the end of cooking, add peas and carrots.