Heat the vegetable oil in a large skillet over medium heat. Add the beef cubes and brown them on all sides for about 5 minutes, then transfer the meat to the slow cooker.
Add the sliced onions, carrots, potatoes, minced garlic, tomato paste, thyme, bay leaves, salt, and pepper to the slow cooker. Sprinkle the flour over everything and stir to coat.
Pour in the beef broth and stir until the flour dissolves into the liquid.
Cover and cook on low for 8 hours, until the beef is fork-tender and the vegetables are soft.
Stir in the frozen peas during the final 30 minutes of cooking so they warm through without losing their texture. Remove the bay leaves before serving.