Bring water to a boil and add salt.
Gradually whisk the polenta into the water.
Reduce heat and continue stirring until the mixture thickens, about 15 minutes.
Stir in the butter.
Oil a heat proof 9" round baking dish and transfer the mixture to the dish. Refrigerate for two hours or until the polenta sets.
Turn the polenta out onto a cutting board and cut into triangles.
In a large skillet, heat olive oil and 2 tablespoons of butter over medium heat. Add polenta triangles and fry until golden brown, about 2-3 minutes per side.
Remove polenta from heat and drain on racks. Place in a warm oven until ready to serve.