1) Boil the 450ml of water with a pinch of salt. Add the rice, cover and lower the heat. Cook for about 15 minutes. Fluff with a fork when done.
2) On a preheated griddle, roast your poblano chillies for about 10 minutes or until the skins begin to blister and char. Place into a bowl and cover with cling film for about 5 minutes.
3) In a medium skillet, add the butter and saute the onion and red pepper until soft, about 5 minutes. Once cooked, place into a medium bowl.
4) In the same cleaned skillet, toast the pepitas for about 3 minutes. Place into a bowl with the onions, peppers, diced tomato, cooked rice, salt, pepper and coriander. Mix well.
5) Carefully remove the skins from the poblanos. With a paring knife or your fingernail (the poblano will be tender), make a slit in the poblano from bottom to top. Remove and discard the seeds and inner membranes, being careful not to tear the rest of the poblano.
6) With a spoon, stuff the poblanos with the rice mixture. Top with cheese. Cover a section of the griddle with foil and place the poblanos back on the griddle for about 5 to 10 minutes until the cheese melts.
Top with a dollop of sour cream.