Preheat oven to 200°C (fan). Chop sweet potato and cauliflower first, toss in 1 tbsp oil, a pinch of salt, and ¼ tsp turmeric. Spread on a tray and place in the oven to roast for 20–25 minutes until golden at edges.
While the vegetables roast, heat 1 tbsp oil in a non-stick pan. Fry tofu cubes until golden on all sides. Set aside.
In a large pot, heat 1 tbsp oil over medium heat. Sauté onion for 2–3 mins until softened. Add garlic and ginger, cook 1 min. Stir in curry paste, kaffir lime leaves, and lemongrass. Fry 1–2 mins to release aroma.
Add coconut milk, stock, soy sauce, and sugar. Bring to a simmer.
Add carrots and red bell pepper. Simmer uncovered for 8–10 mins until just starting to soften.
Add zucchini and cook for a further 3–4 mins until tender but still bright.
Stir in roasted sweet potato, roasted cauliflower, and tofu. Remove kaffir lime leaves and lemongrass stalk before serving. Add lime juice, taste, and adjust seasoning with extra soy sauce or salt if needed.
Ladle over steamed jasmine rice, garnish with coriander, Thai basil, sesame seeds, and lime wedges.