Brighten up asparagus soup with a drizzle of citrus-spiked crème fraîche.
In large saucepan, melt butter over medium. Add asparagus and shallot. Cook, stirring often, until tender, 5 minutes. Add stock; bring to a simmer. In blender, puree asparagus mixture with lime juice; season. Divide among bowls. In bowl, whisk crème fraîche and lime zest; season. Top soup with lime crème fraîche and chives.