1-First Step: Prep the oven and baking pan. Start by preheating the oven to 425°F. This higher heat is important because it helps the vegetables roast instead of steam. Line a baking tray with parchment paper so cleanup stays easy and the vegetables do not stick to the pan. While the oven heats, wash and cut the produce. Quarter the new potatoes, break the cauliflower into florets, and slice the leeks into half moons. Trim the asparagus and cut it into 2-inch pieces. Thinly slice the lemon so it can roast right on the pan later. If you want to finish with herbs, chop them now so they are ready at the end.

2-Second Step: Arrange the first vegetables in one layer. Spread the potatoes, cauliflower, and leeks across the parchment-lined tray in a single layer. This is important because crowded vegetables trap steam and do not caramelize well. If you are cooking for a bigger group, use two trays instead of piling everything up. Drizzle the vegetables with 1 to 2 tablespoons of avocado oil or olive oil. Then season them with sea salt and black pepper to taste. Toss everything gently so the vegetables are lightly coated, but keep them spaced out on the tray. Good roasting starts with space. If the vegetables overlap too much, they soften instead of browning.

3-Third Step: Roast the sturdy vegetables first. Place the tray in the oven and roast for 25 minutes. During this first round, the potatoes begin to soften, the cauliflower turns golden, and the leeks become sweet and tender. The strong heat helps the edges brown in a way that makes the whole pan taste richer. If your oven tends to run hot, check the tray around the 20-minute mark. You want the vegetables to look lightly browned at the edges, not burned. Stir them only if needed, but keep them in a mostly even layer so they continue to roast well.

4-Fourth Step: Add the asparagus and lemon slices. After 25 minutes, remove the tray from the oven. Add the asparagus pieces and toss everything together so the new vegetables pick up the seasoned oil and roasted bits from the pan. Then lay the lemon slices over the top. Return the tray to the oven for another 10 minutes. The asparagus cooks quickly, so this shorter second roast keeps it bright and crisp-tender. The lemon warms and softens, sending citrus flavor into the vegetables as they finish roasting.

5-Final Step: Finish and serve hot. Take the vegetables out of the oven and check for tenderness. The potatoes should be fork-tender, the cauliflower browned around the edges, and the asparagus bright green with just a little bite. If you like a more savory finish, add a final pinch of salt and pepper while the vegetables are still hot. Sprinkle with chopped fresh herbs if desired. Italian parsley, fresh dill, spring onions, and fresh thyme all work well. Serve right away while the vegetables are warm and fragrant. They are excellent next to roasted chicken, grilled fish, pasta, or a grain bowl. For a hearty main dish to serve alongside these vegetables, try this oven baked chicken legs.