Position one oven rack in the middle of the oven, and the other in the bottom third. Preheat oven to 400º.
Remove sides from springform pan. Trim cardboard to fit snugly within the curved lip of the bottom of the pan. Cover the cardboard with foil so that there is a 2 inch overhang all the way around the edges. Attach the sides of the springform pan. Fit foil halfway up the sides and lightly butter the foil and inside of pan. (doing this fives the cheesecake an even, flat base, making it easier to remove).
In the top of a double boiler over hot, not simmering, water,, melt the white chocolate stirring constantly until smooth. Remove top part and cool chocolate for 5 to 10 minutes.
In food processor (using the chopping blades), combine cream cheese, sugar, lemon, and slat. Process mixture of 30 seconds. Scrape down the sides then process for 1 min more, or until creamy.
Add melted chocolate, sour cream, eggs, and vanilla. Process for 30 seconds. Scrape down sideband process for 1 min more, or until smooth.
Pour batter into prepared springform pan. (You may or may not want to use a crust, I use a gingerbread crust--see recipe). Tap the pan several times on a work surface to deflate any air bubbles.
Place a roasting pan with 4 to 6 cups of boiling water (about 2 inches deep) on the bottom rack (This creates a steamy environment and keeps cake moist). Place the cheesecake on the top rack and cook for 10 minutes.
Lower the oven temp to 300º. Continue baking 45 to 55 minutes--until the cheesecake is firm to touch. Don not open the oven door for the first 45 minutes.
Remove the cheesecake from the oven and set it on a wire rack to cool for 10 to 15 minutes. Raise the oven temp to 350º
In a medium bowl, whisk together sour cream, sugar and vanilla until smooth. Pour over the baked cheesecake and spread evenly with spatula.
Return cheesecake to oven and bake for 3 to 5 min, or until the sour cream topping is set. Remove from oven and run a thin-bladed knife around the inside of the pan to release the cheesecake. (This will help prevent the cheesecake from cracking as it cools).
Place cheesecake in the pan on a wire rack and let cool for 1 hour.
Refridgerate cheesecake in its pan overnight, but at least for 6 hours, until firm.
Make the strawberry sauce. In a medium saucepan, combine 4 cups of strawberries, the water, and sugar. Cook over medium heat, stirring constantly until sugar is dissolved and strawberries start to soften. Raise the heat to med-high and bring to a boil. Boil for 3 to 5 minutes or until strawberries turn to puree.
Strain the hot strawberry mixtures through a sieve into a bowl.
In medium saucepan, make a paste by stirring together a small amount of the strained strawberry liquid with cornstarch. Stir in the remaining strawberry liquid. Cook the mixture over medium heat, stirring constantly, until boiling. Boil for 1 minute then remove from heat and strain space into a bowl. Cool to room temperature.
Slice the remaining strawberries. Stir in the orange liqueur into the sauce and gently fold in the sliced strawberries. Cover and refridgerate. Allow sauce to sit at room temp for at least 30 min before serving.
Remove the sides of the springform pan. Slide two metal cake spatulas underneath the cheesecake and transfer to serving plate.
Cut cheesecake with a sharp, t his knife, dipping the blade into hot water between each slice. Serve with sauce.