Heat your oven to 180°C/Fan 160°C/Gas 4. Fry ½ tsp cumin seeds in a dry frying pan till fragrant. Set to one side. Scrub and halve or quarter the potatoes so they’re all roughly the same size. Fill a pan with boiling water. Add the potatoes. Boil for 7-10 mins till just cooked. Drain.
While the potatoes cook, peel and grate the garlic and ginger. Place in a pestle and mortar with 1 tsp turmeric, 1 tsp garam masala, half the toasted cumin seeds and 1 tbsp olive oil. Grind to form a paste. Peel and thinly slice the onion.
Add the garlicky spices to a hot ovenproof frying pan. Cook for 1 min. Add the onion and cook for 2 mins. Add 1 tbsp olive oil and toss in the drained potatoes. Cook over a medium heat for 5 mins till charred and coated in the spices.
Add the spinach to the potato pan with a splash of water. Cook for 2 mins till wilted, stirring constantly. Take the pan off the heat. Halve the chilli. Scoop out the seeds and white bits. Finely chop it. Stir most of it into the yogurt. Season.
If your pan isn’t ovenproof, transfer the curried potatoes into an ovenproof dish, otherwise, leave them in the pan. Make 4 holes in the potatoes. Carefully crack an egg into each. Spoon over the chilli yogurt. Place in the oven and cook for 10-15 mins till the whites are set and the yogurt is thick.
Halve the tomatoes. Roughly chop the chervil. Place in a bowl with 1 tbsp olive oil and seasoning. Set aside.
Sprinkle the dish with the remaining cumin seeds and a little more chopped chilli. Serve with the tomato salad.