Preheat oven to 350 degrees F (175 degrees C). Lightly grease a medium baking sheet.
Place ground Italian sausage in a large, deep skillet. Cook over medium high heat until evenly brown. Remove from heat.
Drain sausage, and mix in garlic salt, oregano and crushed pineapple.
Arrange English muffin halves in a single layer on the prepared baking sheet. Spread with tomato paste. Layer with the Italian sausage mixture. Top with mozzarella cheese.
Bake in the preheated oven 10 to 15 minutes, or until cheese is melted and lightly browned.
