Combine lentils and broth in medium saucepan; boil, reduce heat, and simmer 20-25 minutes until tender and liquid absorbed. Cool completely.
Heat oil in skillet over medium; sauté onion about 5 minutes until soft. Add garlic, curry powder, and cumin; cook another minute.
Combine lentils, onions, breadcrumbs, parsley, tomato paste, and one beaten egg in a large bowl; season with salt and pepper. Mix well; refrigerate until completely cool.
Preheat oven to 400°F. Roll out pastry; cut each sheet into 2 rectangles. Divide filling among 4 rectangles, centered with a border.
Brush edges with egg wash; top with remaining rectangles and fork-seal edges. Cut small top vents.
Brush tops with egg wash; sprinkle with optional sesame and place on parchment-lined baking sheet. Bake 25-30 minutes until golden brown and puffed.