If using sesame seeds, place them in a small, dry skillet and toast, shaking the pan frequently, until lightly browned. Set aside to cool. Rinse the broccoli and separate the florets from the stalks, reserving the stalks for another use.
Arrange the florets in a vegetable steamer basket or steamer insert. Bring about 1 inch of water to boil in a deep, wide pot. Lower the steamer into the pot, making sure it rests above the water. Cover and cook the broccoli until tender, 4 to 5 minutes. Transfer the cooked broccoli to a serving bowl and drizzle with the sesame oil. Add sea salt to taste, and sesame seeds and stir to combine. Serve immediately.