Fill a steamer basket or cooking pot with water; squeeze lemons pieces into the water. Add the broccoli crowns and seal with tight lid. Boil until broccoli is lightly steamed and tender.
Brush a non-stick frying pan with a light coating of oil (the lightest amount possible). Heat pan, then add 1/3 cup of cheese in a round slightly bigger than the surface of one broccoli crown. Heat until cheese browns and turns into a crunchy crisp—turning down the heat as needed to prevent burning.
Using a spatula, loosen the edges of the frico from the pan and work the entire crisp onto a paper towel. Quickly, while the cheese is hot, fit the crisp over the top of one broccoli crown. Repeat for the other two crowns until all three have thin, lacy cheese tops. Put one teaspoon of sour cream on top of each; garnish with equal portions of bacon. Serve immediately.