Heat oven to 350* Grease bottoms and sides of two 8 inch round pans with shortening; lightly flour. Mix flour, baking soda and salt; set aside. Beat sugar and butter in large bowl with electric mixer on medoum speed, scraping bowl occasionally, until fluffy. Beat in eggs, orange peel and vanilla until smooth and blended.
Gradually beat in flour mixture alternately with buttermilk, beating after each addition until smooth. Spoon into pans.
Bake 18 to 22 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pans to wire rack. Cool completely, about 1 hour.
Meanwhile make Orange Mousse: Sprinkle gelatin over orange juice in 1 quart saucepan. Let stand 1 minute to soften. Stir in sugar. Heat over low heat, stirring frequently, until clear and gelatin is dissolved. Stir in orange liqueur and orange peel. Refrigerate 30 to 45 minutes or until almost set. Beat whipping cream in chilled large bowl on high speed until stiff. Add gelatin mixture to whipped cream; beat on medium speed until smooth.
Place cake layer in center of 9 inch springform pan (there will be space around the side). Pour half of the mousse over cake, letting it fill in around the side. Top with second layer. Pour remaining mousse over cake. Refrigerate at least 4 hours or overnight until set.
Run knife around inside rim of pan to loosen cake; remove side of pan. Garnish cake with orange peel strips. Store covered in refrigerator.