2 lb. small brussels sprouts, trimmed
3 Tbsp. vegetable oil
Kosher salt, freshly ground pepper
3 Tbsp. unsalted butter
3 Tbsp. raw pistachios
2 Tbsp. date molasses or honey
1 tsp. honey
Zest of ½ lime
2 Tbsp. fresh lime juice
½ tsp. crushed red pepper flakes
Lime wedges (for serving; optional)
Place a rack in lower third of oven; preheat to 450°. Toss brussels sprouts and oil in a large bowl to coat; season with salt and pepper. Roast brussels sprouts on a rimmed baking sheet 15 minutes, then shake baking sheet to loosen them. Continue to roast until deeply browned all over, 5–10 minutes longer. Reduce oven temperature to 350° and roast another 10 minutes. Shake baking sheet again, then roast brussels sprouts until the tip of a small knife easily slides through, 5–10 minutes longer (total cook time will be 35–45 minutes).
Melt butter in a large skillet over medium heat. Once butter starts to foam, add pistachios and a pinch of salt and cook, stirring often, until nuts are golden brown and butter solids are browned, about 4 minutes. Remove from heat.
Using a slotted spoon, transfer nuts to paper towels; let cool. Coarsely chop.
Meanwhile, bring date molasses, honey, and lime juice to a simmer in same skillet over medium heat (this will happen quickly), swirling pan to emulsify. Add 1 Tbsp. water and swirl to emulsify, scraping up browned bits with a wooden spoon. Add brussels sprouts; toss to coat.
Transfer brussels sprouts to a platter. Toss nuts, lime zest, red pepper flakes, and a pinch of salt in a small bowl to combine; scatter over brussels sprouts. Serve with lime wedges if desired.
Do Ahead: Brussels sprouts, glaze (without water), and pistachio mixture can all be made 3 hours ahead. Do not combine. Reheat glaze over medium heat until bubbling before adding water and brussels sprouts.