In a large mixing bowl, combine the flour, instant yeast, salt, sugar and ground turmeric. Give it a good mix, then use your hands to mix in the butter and, a little at a time, pour in the warm water.
Pour in just enough water to form a big ball of soft, smooth dough. The dough should be on the drier side, no longer sticking to your hands.
Cover the bowl and let the dough rest in a warm area for 15 minutes. Separate the dough into eight equal balls. One ball at a time, use your hands to flatten each ball until it’s the size of your hands and form a large pocket in the middle.
Lightly dust the pocket with flour, then use a dinner spoon to add two spoons of the split peas crumble, known as dhal puri.
Enclose the dhal puri into the ball of dough. It should look like a ball of dough with dhal puri hidden inside.
Dust the counter surface with flour, then roll out the dough ball stuffed with dhal puri as flat as possible without the dhal puri bursting out of the dough. Aim to roll it out approximately ¼ inch (0.6 cm) flat.
Heat a large flat cast-iron pan (preferably) or a nonstick pan over medium-low heat, coat it with a light layer of oil, then place the flat roti on top. Oil the entire surface of the roti, then flip it and oil the other side.
Flip the roti every 15 to 30 seconds until there are light brown specks on both sides. Place the roti in a container or basket lined with a kitchen towel. Cover the roti with the towel to keep it warm. Repeat these steps for the remaining dough balls.