Slow Cooker Beef Stew

4 pounds bottom round, well trimmed and cut into 2-inch pieces
1 cup all-purpose flour
1/3 cup olive oil (plus more if needed)
2 large onions, diced (2 cups)
1 6-ounce can tomato paste
1 cup dry red wine
1 pound potatoes, cut into 2-inch pieces (about 4 cups)
1/2 pound baby carrots (about 2 cups)
2 cups beef broth
1 tablespoon kosher salt
1 teaspoon dried thyme leaves
1 bay leaf
1 cup frozen peas, thawed

Coat the beef in the flour. Heat a few tablespoons of the oil in a large skillet over medium-high heat. Brown the meat, a few pieces at a time, adding more oil as necessary. Transfer to a 4- to 6-quart slow cooker. Add the onions to the skillet and cook over medium heat until tender, about 10 minutes. Stir in the tomato paste and coat the onions; transfer to the cooker. Pour the wine into the skillet and scrape up any browned bits; add to the cooker. Stir in the potatoes, carrots, broth, salt, thyme, and bay leaf. Cover and cook on low heat for 7 1/2 hours, or on high for 4 hours. Add the peas and heat through.