Pour 750 ml boiling water into a high-sided pan over a medium heat. Bring to the boil. Trickle in the polenta, whisking as you go. Once it’s all in, turn the heat down low and cover. Cook for 30 mins, stirring now and then, till the polenta is thick, creamy and pulls away from the side of the pan as you stir it.
While the polenta cooks, warm a frying pan over a medium heat. When hot, tip in the walnuts. Toast for 3-4 mins till dark and nutty smelling. Tip onto your board and let them cool for a few mins, then finely chop them. Tip them into a bowl.
Peel and grate the garlic clove into the walnut bowl. Zest the lemon and juice half of it. Add most of the zest and all of the juice to the bowl. Finely chop the parsley stalks and leaves and add them to the bowl. Drizzle in 1 tbsp oil and season with salt and pepper. Stir to mix together to make your pesto. Taste, and add more salt, pepper or a squeeze of lemon juice if it needs it.
Chop the broccoli into small florets. Cut the butter into small cubes.
When the polenta has 15 mins left to cook, rub the pork loin steaks with 1 tsp oil each and season. Heat the pan you used to toast the walnuts. Carefully place the steaks into the pan and cook for 5 mins on each side till cooked through and golden brown.
Remove the pork from the frying pan and place on a warm plate. Cover loosely with foil to keep warm. Add the broccoli to the frying pan with one-third of the butter and 4 tbsp water. Bring to a simmer and cook for 5 mins till just tender.
Stir the remaining butter through the cooked polenta. Season generously with salt and pepper.
Spoon the creamy polenta onto 2 warm plates. Top with the broccoli and pork steaks. Dollop over the parsley and walnut pesto and the remaining lemon zest.