Cut the carrots into a julienne and wash the ends of the bean sprouts. Sauté the two juliennes separately in olive oil and season. Drain and cool. Mix the herb leaves (coriander, mint and basil) with the juliennes. Sauté the prawns in olive oil until cooked but still tender. Soak the rice paper wrappers in cold water to soften then transfer to a tea towel. Garnish the centre of each wrapper with the juliennes/herb mixture and two prawns that have been chopped into small pieces. Fold each wrapper into the centre to form a small purse shape then refrigerate until ready to be cooked.
Heat the olive oil in a saucepan, add the prawn heads and colour for 5 mn. Add the crushed garlic, onions, shallots, fresh tomatoes and cook for 2 – 3 mn. Add the tomato purée, cook for 1 mn before deglazing with cognac. Add the white wine and reduce to three quarters then cover with water. Add the parsley stems, lemongrass, thyme, bay leaf then bring to the boil and cook for approximately 20 mn over medium heat. Strain through a china-cap sieve and reduce to three quarters to intensify the flavour. Add the cream and bring to a boil without reducing too much then emulsify using a blender.
Thinly slice the white onions. Finely chop the new pearl (spring) onions (green part only), rapidly sauté in olive oil and season.
Steam the ravioli for approximately 3 mn.
Position a layer of onion in the centre of the plate and top with the warm ravioli. Place the carrot julienne, beet and onion sprouts on top. Draw a line of sauce in front and sprinkle with thinly sliced chilli and new pearl (spring) onions (green part only).