Heat the frying pan on a medium-high heat - don't add any fat. You want the pan hot before you add the lamb
Peel, quarter and chop the onion - not too fine
De-seed and chop the pepper into medium-size pieces - about 1-2cm x ½cm
Wash, trim and slice the mushrooms into medium slices
If your chops have a rind on them you may want to cut it off but don't remove all the fat (I don't usually bother.) If you do want to take some fat off, ad it to the pan for the initial browning
For the casserole:
Brown the chops well in the pan. Make sure they are a good colour on both sides, but don't cook throughYou don't need any additional fat (apart from any you've cut off the chops)
Remove the chops and add the onion, pepper and mushrooms and cook for 2-3 minutes, stirring all the time
Sprinkle the mixed herbs over the vegetables and put the chops back, on the top. Put the lid on the pan. Turn the heat down to medium-low and cook for about 5 minutes to soften the onions and peppers
Add the chopped tomatoes, tomato puree, Worcester Sauce and salt. Stir in without disturbing the chops too much. Replace the lid.
Turn the heat to low and cook for an hour. An extra 30-60 minutes won't hurt
When you're ready to dish up, add ground black pepper to taste and add more salt if necessary.
Notes
Everyday Cooks tip: If your chops are frozen, cook in the same way and add 30 minutes to the final cooking time.