Heat the oil in large pot over medium-high heat. Sprinkle lamb on all sides with salt and pepper. Add lamb to pot and brown on all sides.
Transfer lamb to slow cooker.
Add vegetables. Sauté to soften slightly, about 3-5 minutes.
Mix in tomato & anchovy paste. Mix in cinnamon, juniper berries & salt & pepper. Sprinkle in the flour and coat the vegetables.
Add the stock and vermouth. Bring to a boil to cook off the alcohol and thicken the sauce, stirring occasionally, boil for 3-4 minutes until thick. Pour the vegetable/sauce mixture over the lamb in the slow cooker.
Cook on 3-8 hours - 3 hours on high, 5 hours on medium and 8 hours on low