Heat 2 tablespoons of olive oil in a large pot or wok. Steam the greens in increments in the olive oil, covered and over low heat, until wilted, then drain completely.

Heat the olive oil in a large skillet and cook the onions, stirring, over medium heat until soft, 5 to 7 minutes. Add either the sliced fennel bulb or ground seeds, and cook together with the onions for about five minutes. Add the garlic, tomato paste or paprika, and stir for about 3 minutes.

Add the wilted greens, and simmer over low heat, uncovered, until the greens are soft and all the pan liquids have cooked off, about 20 minutes. Stir in the dill about five minutes before removing from heat. The dish should be fairly dry. Adjust the seasoning with salt and sweet or hot paprika or cayenne. Pour a little fresh olive oil over the greens once they are cooked, if desired, and garnish with feta. Serve with warm pita bread.