Preheat the oven to 180°C.
Cut all the Brussels sprouts in half and toss with olive oil and salt.
Pop these onto a baking tray cut-side down and bake for 30 mins, turning halfway through until caramelised and crisp.
Now, make the sambal. Blend up the red chillies with 2 tbsp of water until smooth and transfer into a bowl. Blend up the shallots, ginger, garlic and lemongrass with 2 tbsp of water until smooth.
Heat up 100ml of vegetable oil in a large wok and add in the red chillies. Cook for 10 mins until the oil is stained red and the chillies darken.
Add in the shallot mix and continue cooking for another 10 mins.
Pour in the tomato purée and cook for 5 mins until the purée has darkened, then add in the chopped tomatoes, brown sugar, fish sauce and 1 tsp salt. Cook for 5 mins or until the oil separates.
Add in the sprouts and toss well. Taste and adjust the seasoning if necessary.
Toast the peanuts and lightly crush them. Sprinkle the peanuts over the sprouts and serve.