1. Position a rack in the center of the oven and heat the oven to 325 degrees. Coat the inside of a tube pan with nonstick baking spray or butter.
2. Sift together the flour, baking soda and salt into a medium bowl.
3. In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl, using a handheld mixer), cream the butter on medium speed until light and fluffy, about 3 minutes.
4. Add the sugar and beat until light and fluffy, about 5 minutes. Add the eggs one at a time, mixing well after each. Add the dry ingredients, 1 cup at a time, mixing well after each addition. Scrape the sides of the bowl.
5. Mix the sour cream, tangerine zest and vanilla together in a small bowl with a fork or small whisk. Add to the batter and mix until smooth. Fill the prepared tube pan with the batter and smooth the surface with an offset spatula. Bake for 45 minutes, then rotate the cake and bake for an additional 30 minutes, or until the top of the cake is cracked and golden brown and a toothpick inserted in the middle of the cake comes out clean. Cool the cake in the pan on a cooling rack for 45 minutes.
6. Invert the cake onto a cooling rack set on top of a baking sheet, to catch any glaze drippings. The cake should still be a little warm to the touch.
To make the first glaze.
Mix 1/4 cup of the tangerine juice, the lemon juice and granulated sugar together in a small bowl. Using a pastry brush, pain the entire surface of the cake with this clear glaze, continuing until all the glaze has been used. Let the cake cool completely, about 1 hour.
To make the second glaze.
1. Whisk together the powdered sugar and the remaining 1/4 cup of tangerine juice in a bowl. Let sit at room temperature for 10 minutes.
2. Pour the glaze very slowly over the top of the cake, so it drips down the sides. Leave the cake uncovered until the glaze sets, about 20 minutes.
3. The cake can be stored, in a cake box or under a cake dome, at room temperature for up to three days; the unglazed cake can be wrapped well in plastic wrap and frozen for up to two months.