I recommend you prepare all the vegetables before cooking. Trim either end off the leek and peel outer layer, if needed, then halve and thinly slice the white and pale green part. Remove stems from chard and spinach and chop both relatively small. Cut the pepper away from the core and cut in thin slices. Grate the zucchini/courgette coarsely. Peel and finely chop the garlic and roughly chop the cilantro and parsley.
Warm the oil in a small skillet/frying pan over a medium heat and add the diced leek, pepper and garlic. Cook, stirring now and then, until the vegetables have softened fairly well - around 3 - 5 minutes. Take care that the leek in particular doesn't burn, reducing the heat and/or adding a little extra oil if needed.
Add the zucchini, mix through, and cook a couple minutes so that it softens and cooks down a little. Add the chard and wilt it down, folding the vegetable mixture over the greens to help them wilt down, then add the spinach and wilt it down as well. Add the cumin, salt, pepper and most of the cilantro and parsley and mix through. If the mixture seems a little dry, add a little water to loosen it up (I find around 1 tablespoon is usually good).
Create two slight indents and carefully pour an egg into each then cover the skillet/pan with a lid. Leave a couple minutes until the egg white cooks but only just as the egg will continue to cook after you takes it off the heat.
Scatter the remaining parsley and cilantro, as well as the feta, over the top and serve.