Preheat oven to 375 degrees. In a bowl combine water, honey, 1 teaspoon of the salt, and sprinkle the yeast over the top. Set aside to foam. Then whisk in 2 tablespoons of olive oil, then sift 1 cup of flour and mix well. Set aside for 1 hour, or until it has a sponge-like texture.
Meanwhile, in a medium skillet, heat 2 1/2 tablespoons olive oil and saute onions until tender, about 5 minutes. Then add the garlic, cumin, and remaining salt to the onions. Stir in the spinach, in small batches, and cook until the spinach is soft. Pour on the lemon juice. Drain spinach in a colander and reserve the cooking liquid. In a large bowl, place 2 cups of the remaining flour, making a well in the center of the flour. Pour the spongy mixture into the well. Knead for 10 minutes, adding enough of the cooking liquid to make it pliable yet firm. Transfer to a oiled bowl, cover with plastic wrap and let rise for 2 hours. Then add the feta cheese to the dough and knead for 1 minute. Add the spinach mixture, sprinkle with the remaining flour, and mix together quickly. The dough is supposed to be moist and loose, don't knead again. Form into a oblong loaf and place the dough on a well oiled baking sheet. Cover lightly with plastic wrap and let proof for 1 hour. Bake the bread for 20 minutes, then reduce the heat to 350 degrees and cook for another 30 minutes.