Slow Cooker Beef and Vegetable Soup

Ingredients

• 1/2 tbsp (salted) butter
• 1/2 tbsp extra virgin olive oil
• 453 g Stewing beef cubes ((1 lb))
• 1/2 tsp salt (, plus more)
• 1/2 tsp pepper (, plus more)
• 2 Large carrots, (, diced)
• 2 Large stalks of celery (, diced)
• 1 Large onion, (, sliced into sticks)
• 1 Large russet potato ((skin on, scrubbed clean), chopped)
• 1/2 Cup frozen green peas ((you can use fresh too))
• 3 Cloves garlic (, crushed)
• 5-6 Sprigs fresh thyme
• 8 Cups sodium-reduced beef stock
• 1 tbsp tomato paste
• 3 tbsp cornstarch
• 3 tbsp cold water
• Gravy browner (optional)Gravy browner ((optional))