In a wide frying pan or paella dish, sweat the onion in the sunflower oil over a medium heat for 4-5 minutes until it starts to soften. Add the pimenton and the chicken stock infused with the saffron and stir well, seasoning at the same time.
Bring the stock to the boil and add the rice, stirring once then leaving to simmer untouched for roughly 25-30 minutes until the rice is soft, but not mushy.
10 minutes before the rice is cooked, add the asparagus, peas, carrot, runner beans and artichoke hearts. Remove once the vegetables are tender, then adjust the seasoning using salt, pepper and lemon juice.
Spoon onto serving plates and garnish with a lemon wedge before serving.