Whisk the lemon juice, zest and cornstarch in a large bowl. Mix in the melted butter, salt and sugar. Whisk the eggs into the mixture.
Add the bread cubes and mix to allow the bread to soak up the mixture.
Place in a greased 9x9-inch baking dish and bake at 350 degrees for 45 minutes, until center is set and firm.
While the bread pudding bakes, make the syrup:
Mix sugar and cornstarch in a medium saucepan.
Add remaining ingredients and stir constantly over medium high heat until mixture melts and boils. Keep stirring while the mixture boils and sauce thickens.
Let sauce cool (it will continue to thicken while cooling) then drizzle over finished bread pudding.