Combine the flour, brown sugar, butter and salt in a small bowl, and mix with your fingertips until it resembles coarse crumbs. Set aside.
Dissolve the baking soda in 1/4 cup of hot water in a mixing bowl. Add the egg, cane syrup, vanilla extract, and remaining 1/2 cup hot water. Whisk until smooth. Fold in half of the reserved crumb mixture, and set aside.
Preheat the oven to 450 degrees F.
Pour the cane syrup filling into the pie shell, and sprinkle the remaining crumb mixture evenly over the top. Bake for 10 minutes, then reduce the heat to 375 degrees F and bake for 25 minutes longer.
Remove the pie from the oven and let cool for at least 30 minutes. To serve, cut into thin slices and serve with vanilla ice cream on top.
Yield: 8 to 10 servings