In a food processor, whizz together all the ingredients for the houmous, adding about 50ml water to loosen the mixture to your desired consistency. Season, then chill for up to 24 hrs.
In the small bowl of a food processor or with a stick blender, whizz together all the ingredients for the herby oil. This can also be chilled for up to 24 hrs.
Just before you want to serve, heat oven to 200C/180C fan/gas 6 to make the tortilla chips. Mix together the oil, cumin and sumac, brush over one side of each tortilla and season. Cut each one into 8 triangles and arrange in a single layer on a baking tray (you may need to use 2 trays, or cook them in batches). Bake in the oven for 5-8 mins until crisp and lightly golden.
Spread the houmous over a large serving plate, drizzle with the herby oil and scatter over the pomegranate seeds, pine nuts and feta. Serve with the homemade tortilla chips.