Slow Cooker Beef Stew

Ingredients

• 2 Tbsp. olive oil or vegetable oil
• ~2 lbs. well-marbled beef chuck (cut into 1-inch cubes)
• kosher salt & freshly ground black pepper
• 3 Tbsp. all-purpose flour
• 1 large yellow onion (diced)
• 4 garlic cloves (minced)
• 4 carrots (sliced into diagonal pieces)
• 3-4 celery stalks (diced)
• 1 lb. golden baby potatoes (halved or quartered if large)
• 1/2 cup frozen peas (added at the end)
• chopped chives or fresh parsley (for garnish)
• 3 Tbsp. tomato paste
• 1 cup dry red wine (Cabernet Sauvignon or Pinot Noir)
• 4 cups low-sodium beef broth
• 2 Tbsp. Worcestershire sauce
• 1 Tbsp. dijon mustard
• 1 Tbsp. balsamic vinegar
• 1 tbsp each: chopped fresh thyme, rosemary, and parsley ((or 1 tsp dried each))
• 2 bay leaves
• 2 tbsp cornstarch + 3 tbsp cold water (for slurry)
• 3 tbsp cold, unsalted butter (for velvety texture)