Seared Scallops with Brussels Sprouts and Bacon

Blanch Brussels sprouts in a 3- to 4-quart saucepan of boiling salted water , uncovered, 3 minutes, then drain.
Cook bacon in a 10-inch heavy skillet over moderate heat, turning over occasionally, until crisp. Transfer bacon with a slotted spoon to a small bowl and reserve bacon fat in another small bowl.
Add 1/4 cup broth and 1/4 cup water to skillet and bring to a simmer, scraping up any brown bits. Add butter, salt, sugar, a pinch of pepper, and Brussels sprouts and simmer, covered, 4 minutes. Remove lid and cook over moderately high heat, stirring occasionally, until all liquid is evaporated and Brussels sprouts are tender and golden brown, about 8 minutes more. Stir in bacon and remove from heat.
While Brussels sprouts are browning, pat scallops dry and season with salt and pepper. Heat oil with 2 teaspoons bacon fat in a 12-inch heavy skillet over moderately high heat until hot but not smoking, then sear scallops, turning over once, until golden brown and just cooked through, 4 to 6 minutes total. Transfer to a platter as cooked and keep warm, loosely covered with foil.
Pour off and discard any fat from skillet used to cook scallops. Add remaining 3/4 cup broth and simmer, stirring and scraping up any brown bits, 1 minute. Stir cornstarch into remaining 2 teaspoons water in a cup, then stir into sauce along with any scallop juices accumulated on platter. Simmer, stirring, 1 minute, then remove from heat and stir in lemon juice and salt and pepper to taste.
Serve Brussels sprouts topped with scallops and sauce.