For the deep-fried cheese, preheat a deep fat fryer to 190C. Alternatively, heat the oil in a heavy-based, deep-sided pan until a breadcrumb sizzles and turns golden-brown when dropped into it. (CAUTION: hot oil can be dangerous; do no leave unattended.).
Cut the some of the cheese into chunks. Coat the chunks in the flour, then dip in the eggs and dredge in the breadcrumbs. Place in the fryer, in batches if necessary, and cook until golden-brown. Remove and drain on kitchen paper, season with sea salt.
For the salad, make a syrup by heating the sugar with 100ml/3½fl oz water until the sugar has dissolved. Bring to the boil and add the walnut halves and cayenne pepper. Remove from the heat and set aside to cool.
In a frying pan or sauté pan, heat the rapeseed oil until hot. Shallow fry the walnuts until crisp (approximately 30 seconds), then drain on kitchen paper.
Chop half of the celery into small chunks, and slice the remainder into 5cm/2in long strips. Place the olive oil and baby gem leaves into a bowl, then add the celery strips. Toss the celery to coat in the oil and season with salt and pepper. Place the celery chunks and remaining salad ingredients, including the walnuts into a bowl and mix well.
For the mayonnaise, place the egg yolks, mustard and white wine vinegar in a food processor and blend.
With the processor still running, slowly pour in the sunflower oil and olive oil, drop by drop at first, then faster as the mixture thickens, alternating between the two oils as you go. Continue blending until all the oil is incorporated and a thick mayonnaise is formed. Transfer the mayonnaise to a clean bowl and season with salt and pepper.
Just before serving, add the mayonnaise to the salad and mix well.
For the mango and quince sauce, place the chutney and paste into a small food processor and blend until smooth.
Place the hot deep fried cheese on a serving board with the cold cheese. Serve the salad and sauce alongside.