Heat the oil in a saucepan over medium heat. Add onion and cook for 1-2 minutes. then add garlic and herbs and cook for 1 min more. Add pork and beef and cook for 3-4 minutes until well browned. Then add tomato puree, chopped tomatoes, wine and 250 millilitres of water. Bring everything to a simmer and cook for 30 minutes or until reduced and thickened. The sauce should be quite dry.
Season to taste and set aside to cool.
For the cheese sauce – melt butter in a saucepan over medium heat, then add the flour and cook, stirring for 1 min until thickened. Gradually add milk, stirring all the time and cook for 2-3 minutes.
Then add the cheeses and stir until smooth. Season to taste, then remove from heat and set aside to cool slightly.
Next, bring a saucepan of salted water to the boil and cook lasagne sheets until al dente. Drain and rinse in cold water. Pat sheets dry with kitchen paper, then cut each sheet to the same size as your bread slices.
Butter a slice of bread on a chopping board, then flip bread and place lasagne sheet on unbuttered side. Top the pasta sheet with 1/4 mince mixture, then 1/4 Cheese sauce, again leaving a 1 centimetre border.
Top with a third lasagne sheet then a second slice of bread, butter side up.
Repeat the layering process with all the remaining ingredients to make 4 sandwiches.
Grease and heat a toastie maker. When heated, add the sandwiches, working in batches if necessary. Then close the toastie maker and cook until golden and crisp. Serve toasted lasagne sandwiches immediately.