Malaysian Flatbread (Roti Canai) with Curried Lentil Dip

Ingredients

• 4 cups bread flour
• 2 tablespoons white sugar
• 1 1/2 teaspoons kosher salt
• 1 large egg, beaten
• 3 tablespoons unsalted butter, melted
• 1 1/4 cups water
• 2 teaspoons vegetable oil
• 2 tablespoons unsalted butter
• 1/2 cup diced yellow onion
• 2 teaspoons grated fresh ginger
• 4 cloves garlic, minced
• 1 1/2 teaspoons kosher salt, or more to taste
• 2 tablespoons curry powder
• 1 teaspoon ground paprika
• 1 teaspoon ground cumin
• 1/2 teaspoon black pepper
• 1/2 teaspoon cayenne pepper
• 1/4 cup tomato paste
• 3 cups cold water
• 1 (14 ounce) can full-fat coconut milk
• 1 cup dried red lentils
• 1/4 cup unsalted butter, melted, or more as needed
• 2 tablespoons chopped fresh cilantro
• 1 tablespoon finely chopped serrano pepper