Combine the taco seasoning and flour in a large mixing bowl, then add your beef cubes and toss to coat evenly.
Next, heat your oil in a large, nonstick sauté pan over medium high heat. Once the oil is hot, add the meat to the pan and brown on all sides. (The meat should be in one layer and shouldn't overlap so it gets a nice brown crust so you may have to do this in batches if your pan isn't large enough.)
Once the meat has browned, add it to your slow cooker along with the fire roasted diced tomatoes, tomato paste, lime juice, a little water and fresh chopped cilantro.
Mix everything together so that the meat is well coated; then place the lid on your cooker and cook on high for 2-3 hours or low 4-6 hours. When you're ready to eat, prepare your egg noodles according to package directions and serve with the Taco Beef.
*You can also substitute precut beef cubes for the beef bottom round. Cook on high for 2-3 hours or low for 6-8 hours.