Wash the collard greens or kale thoroughly. Remove any tough stems and chop the leaves into bite-sized pieces. Set aside.
Heat the vegetable oil in a large skillet or pot over medium heat.
Add the chopped onion and cook until translucent.
Stir in the minced garlic and cook for another minute.
Add the diced tomato and bell pepper (if using). Cook until the tomato softens and the bell pepper is tender, about 5 minutes.
Stir in the ground cumin, paprika, turmeric, salt, and black pepper.
Add the chopped collard greens or kale and mix well with the spices.
Pour in the water or vegetable broth. Cover and cook for about 10-15 minutes, or until the greens are tender and cooked through. Stir occasionally, adding more water or broth if necessary.
Adjust seasoning if needed.
Enjoy your meal!