Heat oven to 200C/180C fan/gas 6.
Spread the tomatoes on a baking tray
and roast for 15 mins, then remove.
Heat grill to High.
Meanwhile, soften the onion and
oregano in the oil, stir in the rice and
stock, and boil for 15 mins, stirring
occasionally, until the rice is cooked.
Mix the avocados, herbs, shredded
lettuce and lemon juice.
Stir most of the cheese and tomatoes
into the rice, tip into an ovenproof dish,
scatter remaining cheese and tomatoes
on top with some more oregano and
flash under the grill to brown. Spoon onto
plates with the salad served on the side.