Slow Cooked Lentil and Beef Soup

Ingredients

• 2 tablespoons extra virgin olive oil
• 1 medium onions, chopped
• 1½ pounds beef stew meat
• 2 large carrots, cut into thick slices
• 4 celery stalks, chopped
• 2 cups diced tomatoes
• 4 cups water (or beef bone broth)
• 1 cup green lentils (or brown lentils)
• 2 teaspoons sea salt
• 2 teaspoons dried thyme
• 1 teaspoon dried marjoram
• ½ teaspoons black pepper
• 2 teaspoons red wine vinegar (optional)
• ½ cups parsley, chopped