Bring a large pot of water to a full boil.
Place the banana peels in a medium-large mixing bowl. cover with the boiling water. Reserve the rest for cooking the cauliflower.
Boil the cauliflower and leaves for 5 to 7 minutes or until tender.
Gently stir 1/2 teaspoon turmeric into the bowl with the banana peels . Let them sit until softened and cool enough to handle, around 30 minutes.
Drain the cauliflower and set aside.
Prepare the curry paste: Place the red onion, ginger, garlic and chile into a blender. Add the cilantro stems, cinnamon and remaining 3/4 teaspoons turmeric. Add 1/4 cup of the coconut milk or just enough to blend ingredients into a paste. Blend until smooth. Set aside.
Drain the banana skins and squeeze out any excess liquid. Cut them into bite sized pieces. and set aside.
Heat the oil in a wok or medium sized skillet over medium-low heat. When the oil is hot, add the curry paste and stir fry for 7 minutes.
Add the tomato paste and cook, stirring, for 3 minutes. Add the rest of the coconut milk, the lemon juice, and sugar. Stir gently until well mixed. Cook, uncovered, for 5 minutes, to allow the sauce to deepen and thicken a bit.
Add the banana skins and stir in. Reduce heat and let curry simmer for another 10 minutes, or until the sauce has thickened and the banana skins are soft. Add the cauliflower florets and leaves and cook until well heated.
Taste and adjust for seasoning as needed. Garnish with the reserved chopped cilantro leaves and serve with rice and naan bread, if desired.