1. Preheat oven to 375 degrees F / 190 degrees C. To make the crust: Butter a 9-by-3-inch spring-form pan. In a food processor, pulse graham crackers until fine crumbs form; add melted butter, sugar, and salt, and pulse to combine. Press crumb mixture firmly into bottom using the back of a measuring cup. Bake until set - around 10-12 minutes - let cool. Reduce oven to 300 degrees F / 150 degrees C.
2. Set a kettle of water to boil. To make the filling: Using a food processor, blend cream cheese and sugar till smooth. Add lemon zest and juice, and salt. Add the sticky inner seeds of the vanilla bean. (Stick vanilla bean pod in your sugar jar for vanilla scented sugar.) Add in eggs, one at a time, scraping down side of bowl after each addition. Add in sour cream.
3. Wrap entire underside of pan in foil. Use multiple sheets if needed. Make sure the foil is very secure. Pour in filling; place in a roasting pan. Place the roasting pan in the oven. Gently pour in boiling water to come halfway up side of spring-form. Bake until just set in center, about 1 ¾ hours. Remove pan from water.
4. Whisk the sour cream and sugar together. Then put about ⅓ cup of the mix into a separate bowl and add ColorKitchen colour, after mixing with ¼ -½ tsp glycerin or water to dissolve.
5. Cover the top of the warm cheesecake with the white sour cream mix. Spread smooth. Put the coloured sour cream into a pastry bag or a small ziplock bag with the corner cut off. Pipe the mixture into small lines across the entire top of the cheesecake. Then, using a butter knife, begin dragging the knife through the lines in the opposite direction.
6. Place the cheesecake, without water, back into the oven for 10 minutes to set the topping. Let the cheesecake cool completely. Run a paring knife around the edge of the cheesecake to loosen from pan. Refrigerate until completely cold. Once chilled, carefully remove the edge of the spring-form pan. Use a spatula to smooth sides of cheesecake. Keep cheesecake covered with plastic wrap in the fridge for up to 5 days.