Add 2 tablespoons of oil to a large rondeau pot over medium-high heat and roast the tomatoes, tomatillos, garlic, and onion sliced in half until browned on all sides, which takes about 10 to 15 minutes total.
Remove the vegetables and then add the cumin seeds and cook over low heat just for 1 to 2 minutes until lightly toasted. Set aside on top of the vegetables.
Next, season some top round beef that has been cut into smaller chunks with salt and pepper.
Add 2 more tablespoons of oil to that same rondeau pan over medium-high heat and sear those chunks of beef until they are well browned on all sides, which takes about 10 to 15 minutes. Set the beef aside.
In that same pan add a peeled onion that has been medium-diced and brown well for about 20 minutes over low to medium heat.
Deglaze the pan with beef stock and season well with salt and pepper.
Add the seared beef back into the pan and cover and cook on medium heat for about 60 minutes or until the meat easily shreds apart.
With about 20 minutes or so left in the beef braising process, remove the seeds from some chiles de arbol and guajillo chile and add them to the rondeau pan with the beef and cook just until reconstituted and softened.
Set the beef to the side on a plate and add the softened chiles to a blender along with the original roasted tomatoes, tomatillos, garlic, onions, and cumin seeds, as well as about 1 cup of the braising broth and puree until completely smooth. Set aside. See notes.
Pour out the remaining broth into another pot and keep warm.
In the same pot add the remaining 2 tablespoons of oil and sauté the potatoes, zucchinis, carrots, and swiss chard over medium-high heat until very lightly browned, which takes about 5-7 minutes.
While the vegetables are sautéing, shred the beef with two forks.
Once the vegetables are lightly browned, add in the shredded beef, warm braising beef broth, and pureed vegetable mixture. Adjust the seasonings with salt and pepper.
Serve in a bowl by itself or alongside some Mexican rice and hot corn tortillas.
Notes
Make-Ahead: You can make this recipe up to 1 day ahead of time, just follow the reheating instructions below.How to Store: You can store this picadillo covered in the refrigerator for 4 to 5 days. This will also freeze covered for up to 6 months. Thaw in the refrigerator before reheating and serving. How to Reheat: Add the desired amount of picadillo to a medium-size sauce pot and cook over low heat until hot. Adjust the seasonings with salt and pepper and serve.You can substitute the top or bottom round beef with ground beef, which will make this recipe preparation much quicker.Some other vegetables you can add are green beans, chayote, mushrooms, cabbage, and/or peas.Additional chiles you can use are chipotles or ancho chiles.When blending anything hot, you must remember to remove that center cap to the top of the blender so that it does not build up pressure and explode. Also, remember to start on low speed and then turn it up once it gets going.