1. In a large pot, heat oil over medium heat and toast the fideo pasta until golden brown. Remove and set aside.
2. In the same pot, brown the ground beef until fully cooked. Remove excess fat if needed.
3. Add chopped onion, diced red bell pepper, whole serrano pepper, and minced garlic to the beef. Sauté until vegetables soften.
4. Stir in diced potatoes and chopped tomatoes.
5. Blend chicken broth, bouillon, oregano, and tomatoes separately until smooth, then pour into the pot.
6. Bring the mixture to a boil, then reduce heat and simmer for about 20 minutes until potatoes and tomato foam soften.
7. Stir in the toasted fideo pasta and chopped cilantro.
8. Simmer an additional 10-15 minutes until pasta is tender.
9. Season with salt and pepper to taste.
10. Serve hot, garnished with avocado slices, crumbled queso fresco, and Mexican crema if desired. Warm tortillas on the side.