In a large heatproof bowl, mix together the peppercorns, chilli flakes, fried shallots, garlic, spring onion, star anise, five-spice, sesame oil, sesame seeds and tomato paste. Set a fine-meshed sieve over the top. Being careful of spitting, pour the hot oil over the lot. Add the soy sauce and vinegar to taste, then leave to infuse. Once cool, pull out the star anise. The longer the oil stands, the more intense the heat and flavour will be. Store in the fridge, in a clean sealed jar.