Preheat the oven to 180°C. Poke the sweet potatoes all over with a knife, place on a microwave-safe plate and microwave on high for 10 minutes. Cut in half down the length and set aside to cool.
Heat one tbsp of the olive oil in a large, oven-proof frying pan over medium-low heat. Once the oil is hot, add the onion to the frying pan with a pinch of salt and cook for 10 minutes, stirring often, until softened. Add the spinach to the frying pan and stir through until wilted. Tip into a medium bowl.
Scoop the sweet potato flesh out of the skin and into the bowl. Add the remaining oil, cumin, coriander, chilli flakes and lemon juice. Roughly mash together with a fork and season with salt to taste.
Wipe out the frying pan and then place back over a high heat. Lay the halloumi slices in the frying pan and leave to cook until golden underneath then flip and cook on the other side until golden. Remove from the frying pan and set aside.
Tip the mashed sweet potato mixture into the frying pan and make four wells. Crack the eggs into each well, place into the oven and bake for 15-20 minutes until the whites are set but the yolks are still runny.
Meanwhile stir together all the dressing ingredients in a small bowl. Once the eggs have baked, remove from the oven, drizzle with the tahini dressing and sprinkle with torn pieces of halloumi.