Heat half of the oil in a large saucepan over medium-high heat.
Add the potato and cook, stirring, for 5 minutes or until golden.
Remove and set aside on a plate.
In the same pan, heat the remaining oil over medium heat.
Add the onion and garlic, and cook, stirring, for 3 minutes until the onion softens.
Stir in the curry paste and cook for 1 minute, or until fragrant.
Add the coconut milk and stock to the pan, bringing the mixture to a boil.
Add the roasted cauliflower, beans, and sweet potato.
Reduce the heat to low and simmer, uncovered, for 10 to 12 minutes until the vegetables are tender.
Incorporate the tofu, fish sauce, lime juice, and half of the coriander.
Simmer for 2 more minutes until everything is heated through.
Serve the curry over rice, garnished with the remaining coriander and lime wedges on the side.