Cut all the vegetables into about 2cm cubes and add to a large roasting tin.
Season with pepper, paprika, rosemary and the oil and roast for 20-25 minutes until soft and golden.
Meanwhile, grill the bacon (if using) until crispy and chop it into 2cm pieces.
Once the vegetables are cooked, stir through the bacon and lentils and place the the cubes of halloumi on top and return it all to the oven for about 10 minutes.
Make the dressing by shaking all the ingredients together in a jar.
Remove the tin from the oven, tip into a serving dish and eat hot or cold drizzled with the dressing.