Make the chermoula by placing all the ingredients for it in a chopper and chop/blend to a fairly fine mix.
Slice both onions and 4 of the tomatoes into rings.
Chop the other tomato into small cubes, as you can see in the images.
Line your tagine (or saucepan) with some of the onion rings to form a single layer.
Follow this with all the tomato rings, even if you form 2-3 layers.
Then lie the okra all around the base, coming together in the middle to form a cone shape. Don't worry too much about a perfect cone, given the different lengths of the okra, this won't be all that easy.
Scatter the chopped tomatoes all over.
Finish by pouring the chermoula all over the okra.
Place the tagine (or saucepan) on the stove and heat on medium heat to bring to a simmer. Don't forget the diffuser under the tagine!
When the content of your pot has come to a simmer, lower the heat down to low and simmer slowly until the okra are all cooked. This will take only about 15 minutes in the saucepan and 20-25 minutes in the tagine, depending on how cooked you like your okra. Remember that the vegetables will continue cooking even after you take it off the heat. So always take it off earlier, rather than later.
While the tagine is cooking, heat the 1 tablespoon of olive oil in a small frying pan on medium heat and fry the onions for a good 15 minutes until they are a golden colour with burnt/brown bits. Turn the heat down if you have to, if they are browning too quickly. Set aside when done to serve.
Top with the caramelised onions and scatter the chopped coriander leaves all over and serve with some fresh bread, couscous or as an accompaniment, as mentioned above.