1 tsp freshly ground black pepper, plus more to taste
1 tsp ground cumin
½ cup canola oil
18 corn tortillas
Thinly sliced green cabbage
Crumbled cotija cheese, for serving
Puree cilantro, oregano, sugar, tomatoes, jalapeños, smashed garlic, and ⅔ cup water in a blender until smooth; set salsa aside.
Bring a medium saucepan of salted water to a boil, add potatoes, and cook until tender, about 25 minutes. Drain potatoes and transfer to a large bowl.
Add minced garlic, butter, salt, pepper, and cumin. Mash until smooth. Set potato mixture aside.
Heat oil in a 12" skillet over medium high heat. Spread 1 heaping Tbsp potato mixture over half of each tortilla, and fold over to form a taco. Working in batches, add tacos to oil and fry, turning once, until golden brown and crisp, about 3 minutes.
Stuff cabbage, tomatoes, and cotija into tacos; drizzle with salsa before serving.