Fry the diced potatoes in 1/4 cup of preheated oil at medium heat for 20-25 minutes. Cover them as the cook. Stir as needed. When fork tender, drain onto a plate lined with paper towels. Set aside.
In a deep skillet at medium/high heat add the ground chuck. Season with 2 tsp each of salt, pepper and garlic powder. Cook for 15-18 minutes, draining off excess fat as needed. Once browned, reduce heat to medium.
To the beef, add the poblano, onion, jalapeno and garlic. Saute for 6-8 minutes. While the vegetables saute, tear the guajillo peppers into pieces. Place in bowl. Cover with some water and microwave for 5 minutes.
When ready, roughly chop the tomatoes and transfer to the blender. Remove the chiles from the microwave and pour into blender, including the water they cooked in. Add in the oregano, cumin and bouillon. Mix on high until sauce is smooth. Taste for salt.
Pour the sauce from blender into the skillet with beef. Stir well to combine and let it simmer for 10 minutes. Fold in the previously fried potatoes. Cook for another 5 minutes. Cover beef and remove from heat. Set aside.
Preheat oven to 400 degrees F.
Preheat a large griddle(comaat medium heat for 5 minutes. While the griddle preheats, brush the tortillas on both sides with oil and stack onto a plate.
Lay 6 tortillas onto the hot griddle. Flip tortillas over after 30 seconds. Fold closed to form a taco shape. Continue cooking until tortillas begin to get crispy. Or if you prefer them to be softer, you can remove them now. Transfer taco shells to a baking sheet.
Fill the bottom of the shells with some cheese first. Then add beef filling. Arrange in baking dish so they stand up, open side up. Once you have all the filled tacos arranged, top generously with shredded cheese. Bake in preheated oven for 10-15 minutes or until cheese melts. Garnish with green onion, salsa, sour cream, lettuce and tomato. Serve right away.