Peel and finely chop the onion. Rinse, trim and finely chop the celery. Finely grate the zest from the lemon. Juice it.
Warm a splash of olive oil in a pan. Add the onion and celery. Fry for 6-8 mins over a lowish heat till soft and glossy yet still pale. Stir every now and then.
Tear the leaves off half the lettuce. Rinse and dry in a salad spinner or with kitchen paper. Pop in a bowl. Rinse and halve the cherry tomatoes. Add them to the lettuce and give it all a stir. Put to one side. Fill the kettle and boil it.
Add the risotto rice to the onions. Stir to mix with the onion. Pour 700ml hot water from the kettle into another pan. Crumble in the stock cube. Keep warm over a low heat.
Gradually add the stock to the risotto rice, a ladleful at a time. Cook over a low heat till each ladleful is absorbed before adding more. The rice should be tender with a bit of chew. Stir often.
Heat a splash of olive oil in a frying pan. Fry the fish pie mix over a high heat for 3-4 mins till just cooked through.
Add half the zest and half the lemon juice to the risotto. Stir well. Rinse and dry the baby kale. Add to the risotto. Give it a good stir so it wilts. Taste to check the seasoning. Adjust if you think it needs it.
Dress the lettuce and tomatoes with the rest of the lemon juice and a little olive oil. Top the risotto with the fish pie mix and the rest of the lemon zest. Serve with the salad.