Spinach and ricotta patties with tomato sauce

Spinach patties

• olive oil, for greasing
• 90 g Parmesan cheese, cut into cubes (3 cm)
• 1 - 2 pieces lemon zest (5 x 2 cm), no white pith (optional)
• 200 g fresh baby spinach leaves
• 250 g ricotta, drained
• 1 pinch sea salt
• ¼ tsp ground nutmeg, to taste
• ¼ tsp ground black pepper
• 1 egg
• 90 g plain flour

Tomato sauce

• 1 brown onion, cut into quarters
• 1 garlic clove
• 20 g olive oil
• 400 g canned chopped tomatoes
• 1 tsp dried oregano
• 1 tsp Vegetable stock paste (see Tips)
• 1 pinch sea salt, to taste
• 1 pinch ground black pepper, to taste