Trim stems off brussels sprouts and remove any damaged leaves. With a mandoline, a sharp knife, or a food processor fitted with the 2-mm. slicing disk, cut sprouts into thin slices.
Melt coconut oil in a wok or a dutch oven over medium-high heat. Add mustard seeds and cook just until they start to sizzle and pop, 30 to 45 seconds. Add poppy seeds, chile flakes, curry leaves if using, almonds, and garlic and cook until garlic is fragrant, about 30 seconds more. Add sprout slices, salt, and pepper and stir gently to coat evenly. Turn the heat to medium-low and cook, stirring occasionally, until sprouts start to brown and char a little, 8 to 10 minutes.
Remove from the heat and stir in lime juice. Taste and adjust salt or lime, if necessary. Serve hot or warm.