Heat the oil in a large pot over medium heat. Add the onion and garlic and sauté for 5 minutes until softened. Add the bell pepper and curry paste and cook for another 2 minutes.
Add the vegetable broth, coconut milk, soy sauce or tamari, lime juice and sugar or agave nectar. Bring to a simmer and cook for 10 minutes.
Add the tofu cubes and cook for another 5 minutes until heated through. Taste and adjust seasoning as desired.