Place the oil, ginger, garlic, shallots, turmeric, chillies, lemon grass and half the coconut milk in a food processor and process until fairly smooth.
Heat a large nonstick wok and pour the coconut mixture into it. Stir-fry over a high heat for 3–4 minutes and then add the remaining coconut milk, the stock and lime leaves. Bring to the boil, reduce the heat and simmer gently, uncovered, for 10 minutes.
Add the courgettes and baby sweetcorn to the mixture and simmer for 6–7 minutes. Stir in the tofu, soy sauce and lime juice, season to taste and cook gently for 1–2 minutes.
Remove from the heat and stir in the fresh coriander. Serve in bowls garnished with basil leaves.