Preheat your Blackstone griddle to medium-high heat (about 375°F) and add oil.
Add diced potatoes and season with Lumberjack seasoning and garlic powder. Spread into an even layer, cover with a dome, and cook for 8–10 minutes, stirring occasionally, until tender.
Remove the dome and cook uncovered for 5–7 more minutes, stirring occasionally, until golden and crispy. Push to one side.
Add chorizo to the griddle and break it up as it cooks. After about 2 minutes, add sliced onion and cook for another 5–6 minutes, until the chorizo is fully cooked and onions are soft.
Mix the chorizo and onions into the potatoes and keep warm on low heat.
Lower one section of the griddle to low (about 300°F). Lightly oil and cook tortillas for 2–3 minutes per side until crispy like tostadas. Remove and set aside.
In another lightly oiled area over medium-low heat, cook eggs sunny-side up for 2–3 minutes, until whites are set and yolks remain runny.
Assemble by topping each tostada with the potato-chorizo mixture, a fried egg, salsa, cotija cheese, sour cream, and cilantro. Serve immediately.