In a large pot (one that accomodates your steamer), bring about 2 inches of water to a boil over high heat.
Meanwhile, trim and cut the broccoli into 2-inch florets. When the water is boiling, steam the broccoli in a steamer basket until it's just cooked, 7 to 9 minutes.
While the broccoli steams, heat the oil in a small saucepan over medium-low heat. Add the olives, garlic, salt and dried oregano. Cook until the garlic is lightly colored, 3 to 5 minutes. Remove the pan from the heat. Finely grate the zest from the lemon; set aside. Squeeze 4 tsp. juice from the lemon and add the juice to the oil. Season with pepper. (I left out the zest. --mrm.)
Spread the broccoli on a warmed serving platter. Reheat the dressing until it begins to bubble and then pour it over the broccoli. Sprinkle with the lemon zest and fresh oregano. Serve immediately.