1. Preheat oven to 400°F. Position the rack in the center. Cut the potatoes into uniform 1-inch cubes — consistent size is the key to every piece finishing at the same time.

2. Add the cut potatoes and trimmed asparagus to a large mixing bowl. Drizzle the olive oil over everything, then add the minced garlic, dried oregano, salt, and pepper. Toss with your hands until every single piece of potato and every asparagus spear has an even coat of oil and seasonings — no dry spots.

3. Spread the seasoned vegetables in a single layer on a large rimmed baking sheet. Give every piece its own space — no overlapping. Crowded pieces steam each other instead of roasting and come out pale and soft. Use two pans if needed.

4. Roast on the center rack for 20–25 minutes. At the 12-minute mark, pull the pan and use a spatula to flip and toss the vegetables. This exposes fresh sides to the hot pan and gives you golden, caramelized surfaces on multiple sides rather than just the bottom.

5. The potatoes are done when a fork slides through them easily and the edges look golden and crispy. The asparagus tips should look slightly charred. Remove from the oven, drizzle the fresh lemon juice evenly over the pan, scatter the chopped parsley on top, and serve immediately while everything is hot and fragrant.