Tiella pie with mussels and potatoes

Name: Tiella pie with mussels and potatoes
Ingredients: 1 1/2 teaspoon dry yeast; 3/4 cup water; 2 cups all purpose (AP) flour; 1/4 cup olive oil (or vegetable oil); 1 pinch salt; 1/2 teaspoon zest of a lemon; 1/4 teaspoon sugar (optional); 2 green onions (white and green parts sliced); 1 clove of garlic (minced); 2 tablespoons olive oil; 2 small potatoes (boiled and diced); 8 ounces mussels (boiled, from 2lbs mussels with shells); 1/2 teaspoon saffron (powder); 1/4 cup parsley (chopped); 1 tablespoon lemon juice; 2 tablespoons heavy cream