Blanching the broccoli spears before assembling it into this dish helps the broccoli retain its bright green color during the sautéing stage. If you prefer not to do this extra step, plan on an extra 5 minutes or so to cook the broccoli. There are just a few ingredients here, but the combination of flavors is very nice. Italian cuisine relies heavily on anchovies - but for all of you anchovy haters, we guarantee you won't know they're in this dish!
Bring a large pot of water to a boil over high heat and add 1 tablespoon of salt. Blanch the broccoli for 3 minutes, then drain and plunge the broccoli into a bowl of ice and water to stop the cooking process and set its bright color. When the broccoli is cool, drain thoroughly and set aside. This step can be done several hours ahead of serving.
Heat the oil in a large skillet over medium heat, then add the onion and red pepper flakes. Cook, stirring frequently, until the onions soften, about 5 minutes. Add the anchovy paste, garlic, and thyme, and continue cooking another 2 to 3 minutes, stirring often.
Add the broccoli to the skillet, raise the heat to medium-high, and cover the pan. Cook until the broccoli is crisp-tender, 5 to 10 minutes, depending on the size of your spears. Just before serving, squeeze the lemon over the broccoli, if you like. Serve hot.