Peel and wash the potatoes and cut them into bite-size cubes. Place the potatoes in a deep pot with enough cold water to submerge them, along with 1 tsp salt and the turmeric. When the water starts boiling, continue cooking for 5 minutes and then drain and set aside.
Preheat around 5cm of vegetable oil in a deep pot over high heat.
Toss the potato cubes with the cornstarch and deep fry, cooking in batches if necessary, only until the exterior is golden brown as the cubes were already partially cooked. Take them out and place on some paper towels to absorb the excess oil and continue cooking the remaining potatoes. Optional: If you want to maximize how crispy these get, you could air fry them after this point for around 5-10 minutes, being careful not to darken them too much.
In a small bowl, stir the juice of 1 lemon along with 3/4 tsp salt and the remaining ingredients. Place the potato cubes in a large bowl, pour over the herb mixture and toss to mix. Enjoy!