Break off the tough ends of the asparagus and discard, place the asparagus stalks in a zip-top bag and add the oil. Gently, roll the asparagus around to coat evenly.
Spread the asparagus spears in a single layer, on a baking sheet. Transfer to the upper rack of the oven and roast the asparagus for 5 to 10 minutes depending on your desired doneness.
Remove the asparagus from the oven and transfer to a serving plate. They will be bright green, tender and crisp if you cook them for 5 minutes (our favorite). If you cook them much longer, they will get soft and loose some of their bright green color. Sprinkle with salt and squeeze lemon juice over them. Garnish with the lemon slices.
Notes
To get the asparagus more evenly roasted, place a rack on top of the baking sheet and then spread the asparagus out on top of the rack. The rack will allow hot air to circulate around the asparagus stalks as they roast.