Begin by browning the ground beef in a large skillet over medium-high heat, ensuring it is cooked through. Drain any excess fat before transferring the meat to a large bowl. Mix in the refried beans, dried oregano, ground cumin, and garlic powder until well combined.

Layer the lasagna noodles in the bottom of a 9x13 inch baking dish, placing four uncooked noodles in the base. Spread half of the seasoned beef mixture over the noodles, then place another four uncooked noodles on top. Add the remaining beef mixture and cover with the final layer of noodles. In a separate bowl, combine the salsa and water, then pour the mixture over the entire dish.

Cover the dish tightly with aluminum foil and bake in a preheated oven at 350°F (175°C) for 1 ½ hours, or until the noodles are fully cooked and tender.

Once the lasagna is baked, mix the sour cream, chopped green onions, and sliced black olives in a medium bowl. Spread this topping over the lasagna, then sprinkle with shredded Pepper Jack cheese. Return the dish to the oven for an additional 5 to 10 minutes, or until the cheese has fully melted and the topping is bubbly.