Cake
1 1/4 pound (565 grams) rhubarb, trimmed and cut into 1/2-inch lengths on the diagonal
1 1/3 cup (265 grams) granulated sugar, divided
1 tablespoon lemon juice (psst, skip ahead and zest it for the cake before you cut it)
1/2 cup (1 stick, 4 ounces or 115 grams) unsalted butter, softened
1/2 teaspoon finely grated lemon zest
2 large eggs
1 1/3 cups (165 grams) all-purpose flour
1 teaspoon baking powder
3/4 teaspoon table salt
1/4 teaspoon ground ginger
1/3 cup (80 grams) sour cream

Crumb
1 cup (125 grams) all-purpose flour
1/4 cup (50 grams) light brown sugar
1/8 teaspoon table salt
1/4 teaspoon ground cinnamon
4 tablespoons (1/2 stick, 2 ounces, or 55 grams) unsalted butter, melted