Mix the marinade ingredients together in a bowl and set aside.
Dry fry the aubergine in a large wok or frying pan on medium heat for about 3-4 minutes until the edges start to colour. Add the peanuts and cook for a further 3 minutes or until toasted.
Remove the aubergine and peanuts from the pan and set aside.
Return the pan to the heat and add the sesame oil. Once hot, add the spring onions, ginger, garlic and chillies (if using) and cook for 2-3 minutes or until the onions are starting to soften.
Add the marinade, stir, and cook for another minute. Add the aubergine and peanuts back into the pan, along with a splash of water. Simmer for 10 minutes until cooked through.
Stir through the spinach, then remove from the heat and allow the spinach to wilt for a minute. Garnish with chopped peanuts.