Slow Cooker Vegetarian Mushroom Gravy | Savory

Ingredients

• 2 tbsp olive oil
• 1 medium red onion, roughly chopped
• 1 (8 oz) pkg sliced baby bella mushrooms
• 1 (3.5 oz) pkg sliced shiitake mushrooms
• 3 tbsp all-purpose flour
• 2 3/4 cups low-sodium vegetable stock, plus more if needed
• 1 tbsp reduced-sodium soy sauce
• 1/2 tsp fresh thyme leaves, plus more, if desired