In a large pot (one that accommodates your steamer), bring about 2 inches of water to a boil over high heat.
Meanwhile, trim and cut the broccoli into 2 to 3 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 teaspoons juice from the lemon and add the juice to the oil. Season with pepper.
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.
Notes
If you are preparing this dish as gluten-free, just be sure to use a brand of olives that is known to be GF.