In your stand mixer bowl fitted with a dough hook, add the salt, sugar, 1/3 cup cooking oil, and pour in the 5 cups of hot water. Stir briefly to dissolve.
Turn the mixer on low speed and add the 10 cups of all-purpose flour in two large batches, letting it knead for 5–7 minutes until a soft, unified dough forms.
Transfer to a lightly floured countertop and knead manually for 1-2 minutes until completely smooth and pliable.
In a small bowl, whisk together the 1/2 cup of warmed oil and 3/4 cup of flour until it forms a completely smooth, pourable paste.
Divide the dough into 12 to 15 equal portions and roll them into tight balls. Roll each ball out into a thin circle using a rolling pin.
Spread a thin layer of the oil-flour paste across the circle. Roll the dough up tightly into a rope, then coil it into a snail-shell shape. Let rest for 5 minutes.
Roll each coiled piece out a second time into an even circle about 1/8 inch thick.
Heat a dry pan over medium-high heat. Place the chapati on the pan without oil and cook for 1-2 minutes until bubbles form, flip for 30 seconds, then remove. Repeat for all pieces.
Return each pre-cooked chapati to the hot pan one at a time, add 1 tablespoon of oil, and shallow fry both sides until flaky, crispy, and beautifully golden-brown. Serve warm.