Preheat oven to 350˚F.
Place all dry ingredients, except poppy seeds, into a large mixing bowl and whisk together. Set aside.
In a stand mixer with a paddle attachment or an electric hand mixer cream together butter and sugar. Add eggs and yolk, one at a time, scraping down bowl after each addition.
Stir in buttermilk, lemon juice and vanilla and mix until well combined. Pour Flour mixture into butter mixture and stir until just combined. Fold in poppy seeds.
Pour mixture into a prepared bundt pan and bake for 50 minute to 1 hour and 10 minutes or until golden brown and toothpick comes out clean when inserted into the center of the cake.
Remove from oven and allow to cool for about 30 minutes.
Run a knife along edge to loosen and invert onto plate or cake stand.
For glaze: Place sugar in a mixing bowl and add tangerine juice and milk. Stir together with a fork until complete combined. Stir in vanilla and zest. Add more sugar or tangerine juice, 1 tablespoon at a time, to adjust consistency, if needed.(should be pourable)
Pour glaze over cake and allow glaze to set, 15 to 20 minutes.
Slice and serve.