Beef Stew with Mashed Potatoes

3 cloves garlic, minced
2 tablespoons tomato paste
4 cups beef broth
1 teaspoon salt
1/2 teaspoon black pepper
1 teaspoon dried thyme
1 teaspoon paprika
1 bay leaf
2 tablespoons all-purpose flour (optional, for thickening)
1 cup frozen peas (optional)

For the Mashed Potatoes:

2 pounds potatoes, peeled and cubed
4 tablespoons butter
1/2 cup milk or heavy cream
1 teaspoon salt
1/2 teaspoon black pepper

Instructions: