Prep the pan. Line an 8x8-inch square baking pan with parchment, leaving overhang on two sides for easy lifting. Preheat the oven to 325°F (165°C).

Make the crust. Stir graham crumbs, sugar, ginger, and salt with melted butter until the mixture resembles damp sand. Press firmly into an even layer in the pan. Use the bottom of a measuring cup to compact it well.

Par-bake the crust. Bake for 8–10 minutes until just set and fragrant. Set aside to cool slightly while you prepare the filling.

Beat the filling. In a bowl, beat softened cream cheese and sugar until smooth and creamy, about 2 minutes, scraping the bowl. Mix in sour cream, vanilla, lemon zest, and salt until combined. Beat in eggs one at a time on low until just incorporated. Do not overmix.

Bake the cheesecake layer. Pour the filling over the crust and smooth the top. Bake 20–25 minutes, until the edges are set and the center still wobbles slightly when the pan is nudged.

Cool and chill. Let the pan cool on a rack for 1 hour, then refrigerate at least 3 hours, preferably overnight, until fully set.

Stew the rhubarb. In a small saucepan, combine rhubarb, sugar, and water or orange juice. Cook over medium heat, stirring occasionally, until the rhubarb softens and begins to break down, 8–10 minutes. Add lemon juice and vanilla. If using strawberries, stir them in for the final 2 minutes. The mixture should be spoonable, not stiff. Adjust sweetness to taste.

Cool the topping. Transfer the stewed rhubarb to a bowl and let it cool completely. It will thicken slightly as it cools.

Cut into bites. Lift the chilled cheesecake out of the pan using the parchment. Trim edges, then cut into 1- to 1.5-inch squares. Wipe the knife between cuts for clean edges.

Top and serve. Spoon a small dollop of stewed rhubarb onto each piece. Finish with a pinch of flaky salt or crushed nuts if you like.