In a food processor process flour and salt. Add the water and melted butter; process until a crumbly dough forms. Transfer to a lightly floured surface; knead until smooth. Cover; let rest 30 minutes.
Preheat oven to 400 degrees F. Roll dough to 1/8- to 1/16-inch thickness. Using a knife, cut into 21/2-inch rectangles or other desired shape. Arrange on an ungreased baking sheet. Prick several times with a fork. Brush with a little water; sprinkle with smoked salt and poppy seeds and/or black sesame seeds. Bake 10 minutes or until golden. Remove; let cool. Store in an airtight container at room temperature up to 3 days.