Place the potatoes in a large pot and cover completely with cold water. Bring to a boil over high heat. Cook the potatoes until they are fork tender, about 45 minutes. Drain the potatoes and let them cool before handling. 

Place 1 tablespoon of oil in a skillet over medium heat. Once the oil is hot add the onion and fry until golden brown, about 15 minutes. Transfer to a paper towel-lined tray and let cool.

In a small bowl, smash the boiled eggs into a fine mixture using a fork. Place the potatoes into a separate large mixing bowl and use a potato masher or fork to smash the potatoes into a smooth mixture. Add the eggs, onion, lemon juice, turmeric, salt, and pepper into the bowl with the potatoes. Mix until combined well. 

Shape the pastels: Place the flour and water into a small bowl and mix until well combined. Set aside. Lay out a lumpia wrapper onto a clean surface. Cover the rest of the wrappers with a damp paper towel to prevent them from drying out. Cut the wrapper into 2-2 ½ inch thick strips horizontally. Dip your finger into the water and flour mixture and spread a thin layer of it around the edges of the wrapper to help seal the pastel once shaped. Add 1 tablespoon of the potato filling on the bottom edge of the wrapper. Fold the wrapper straight over the tablespoon of filling and press down to seal. Next, fold the bottom left corner of the dough upwards and to the right until it meets the right edge of the dough strip. Now the edge of the dough that has been folded over twice should form a triangular shape (see here for more detailed visuals). Grab the triangle from the bottom right corner and flip it up to the left until the triangle is aligned with the left edge of the strip of dough. Repeat this folding process, continuing to fold the triangle right and then left until you reach the end of the dough. Once the pastel is shaped  press down on the edges to seal it. Transfer the pastel to a large plate and repeat filling and shaping the rest of the wrappers and filling.

In a frying pan over medium-high heat, add about ¾-inch of grapeseed oil. To see if the oil is ready, slowly dip a pastel into the oil. If it starts to sizzle then you know it’s ready. Once the oil is sizzling gently, place enough pastels to fit the pan without overcrowding. Fry for about 1 ½ minutes on each side or until evenly golden brown. Transfer to a paper towel-lined tray and continue frying the remaining pastels in batches adding more oil to the pan if needed.

Serve hot with a side of harissa aioli.