To make the stuffing, grate the cauliflower or pulse it in a food processor until it resembles rice grains.
Heat the oil in a frying pan over medium heat.
Add the diced onion and fry for about 8 minutes until soft and golden.
Stir in the green chiles and ground cumin, and cook for another minute until fragrant.
Add the riced cauliflower and cook for 4-5 minutes, stirring occasionally.
Remove the pan from the heat and stir in the salt, black pepper, and grated Cheddar.
Mix until the cheese is just combined.
Set the filling aside to cool completely.
To make the roti dough, combine the flour and salt in a large bowl.
Add the oil and mix it in with your fingertips. Make a well in the center and gradually add the warm water, kneading as you go to form a soft, springy dough.
Lightly coat the dough ball with a little extra oil, cover, and set aside to rest for at least 15 minutes.
On a floured surface, divide the dough into 12 equal pieces.
Roll each piece into a smooth ball, flatten it, and dust with flour.
Roll out into a 7-inch / 18cm circle.
Spread 2 tablespoons (30 ml / 1 fl oz) of the cooled filling over one half of the circle, leaving a ½-inch / 1cm border.
Fold the empty half over the filling to create a half-moon shape. Press the edges firmly to seal.
Gently roll over the stuffed roti with your rolling pin to flatten it slightly and ensure the filling is evenly distributed.
Repeat with the remaining dough and filling.
Heat a dry frying pan or tawa over medium-high heat.
Place a stuffed roti on the hot pan and cook for 1-2 minutes per side, until golden brown spots appear. Press down gently with a spatula to help it cook evenly.
Transfer the cooked roti to a plate.
Serve immediately with a side of pickle or yogurt.
Let the cauliflower filling cool completely before stuffing. A warm filling can make the dough soggy and difficult to handle.
Don't overstuff the rotis, as they can tear during rolling and cooking. Stick to about two tablespoons of filling per roti.
Keep cooked rotis warm in a foil-lined container or a low-temperature oven while you finish cooking the entire batch.
