In a small saucepan, heat butter over medium heat; cook until browned. Transfer to a small bowl, and let stand.
In a small saucepan, heat oil over medium heat; cook until hot. Whisk in flour, and cook, stirring frequently, until a blond roux forms.
In medium stockpot, bring carrot juice to boil; whisk in roux. Add zest, and cook until reduced by half. Whisk in browned butter; reduce heat to low, and cook for 5 minutes. Add lemon juice, and let cool slightly. Serve warm.
Recipe by Louisiana Cookin' at https://louisianacookin.com/carrot-ravioli-vadouvan-crunch/