Stir together first 8 ingredients in a 6-quart slow cooker. Add thyme sprigs and bay leaves; dollop tomato paste on top. Heat 1 tablespoon oil in a large skillet over medium-high. Add half of beef; cook until well browned, about 6 minutes, turning once. Add beef to slow cooker. Repeat with remaining 1 tablespoon oil and beef. Scatter carrots over beef. Cover and cook on LOW until meat and grains are tender, about 8 hours. Discard thyme sprigs and bay leaves. Ladle stew into 8 bowls; sprinkle with thyme leaves.