Step 1

To prepare the rhubarb: In a medium bowl, stir together the diced rhubarb and sugar. Pour the mixture into a strainer and place the strainer over a bowl. Let the rhubarb drain for 45 minutes, tossing occasionally; reserve the rhubarb and liquid separately.

Step 2

, To make the streusel: In a medium bowl, whisk together the sugar, flour, cinnamon, ginger, and salt. With a fork or your fingers, work in the butter until the mixture is crumbly, then stir in the nuts. Set aside.

Step 3

, Preheat the oven to 350°F. Lightly grease a 9” x 13” pan.

Step 4

, To make the cake: In a large bowl, whisk together the flour, baking powder, salt, and sugar.

Step 5

, Add the butter, stirring or beating gently until the mixture looks sandy.

Step 6

, Mix in the rhubarb juice, vanilla, and lemon zest, then beat in the egg. Scrape the bowl and mix for 30 seconds; the batter will be thick.

Step 7

, Stir in the drained rhubarb by hand, mixing until evenly distributed.

Step 8

, Transfer the batter to the prepared pan and sprinkle the top with the streusel.

Step 9

, To bake the cake: Bake the cake for 47 to 50 minutes, until a paring knife inserted into the center comes out clean. Remove the cake from the oven and cool it on a rack before serving.

Step 10

, Storage information: Store the cake, well wrapped, at room temperature for up to four days; freeze for longer storage.