Preheat oven to 350~F. Melt 1 tb butter; brush over inside of 12 cup Bundt pan. Combine flour, poppy seeds, baking powder and soda. In bowl with mixer at medium speed beat granulated sugar with remaining butter until light and fluffy, about 3 minutes. Beat in eggs, one at a time, until combined. Beat in sour cream, 1/4 cup juice, zest and vanilla. Reduce speed to low; gradually beat in flour mixture until just combined. Pour batter into pan. Bake 45-50 minutes or until toothpick inserted into center comes out clean. Cool 10 minutes. Remove cake from pan; cool completely on rack. Combine confectioners' sugar with remaining juice and zest; drizzle over cake.