Preheat oven to 375°F (190°C).
In a large bowl, combine all-purpose flour and salt.
Cut in cold butter until the mixture resembles coarse crumbs.
Gradually add cold water, mixing until a dough forms.
Divide the dough into 4 equal portions and roll each into a thin circle.
In a separate bowl, mix cooked diced ham, shredded mozzarella cheese, diced bell peppers, diced onions, and tomato sauce.
Place a quarter of the filling onto one half of each dough circle, then fold over and seal edges by pressing with a fork.
Place the hot pockets on a baking sheet lined with parchment paper.
Bake for 25 minutes or until the crust is golden brown and flaky.
Remove from oven and let cool slightly before serving.