This is even nicer than the more traditional steak sandwich, as lamb teams with sweetly caramelised onions for a hearty weekend lunch.
Heat the oven to 180°C/Gas 4. Finely slice the onions and toss in a roasting pan with 2 tbsp olive oil, the balsamic vinegar, salt and pepper. Bake for 30 to 40 minutes until caramelised.
Flatten each lamb fillet or steak with a meat mallet, then cut in two. Combine the extra virgin olive oil, white wine, garlic and oregano in a shallow dish, add the lamb and coat well.
Slice the tomatoes and season with salt and pepper. Beat the mustard into the mayonnaise.
Lightly oil a non-stick fry pan and heat. When it is very hot, add the lamb and sear until crusty, turning once. This will only take a minute or two either side. Season well, and set aside while you toast or grill the bread.
Spread 4 toast slices with the mustard mayonnaise, and arrange the rocket leaves, tomatoes, lamb and caramelised onions on top. Top with the remaining toast slices.
© 2002 Jill Dupleix. All rights reserved.