Slow Cooker French Onion Soup - Slender Kitchen

Ingredients

• 4 sweet onions, sliced
• 2 tbsp butter
• 1 tbsp Worcestershire sauce
• 1 tbsp balsamic vinegar
• 3 garlic cloves, minced
• 2 tsp brown sugar (or Stevia)
• 1/2 tsp pepper
• 1/2 tsp salt
• 3 tbsp all-purpose flour
• 64 oz vegetable broth (or chicken broth or beef broth)
• 2 tbsp fresh thyme