To make the tartine:
- Mix the ricotta with the lemon zest and dill. Season with salt and pepper and set aside.
- Toast the sourdough slices, then rub all over with the cut garlic and drizzle with the olive oil.
- Spread the ricotta on to the bread, arrange the prosciutto on top, then top with the radish slices and asparagus.
To make the basil oil:
- Blend a large handful of basil leaves with some salt and pepper in a food blender.
- Add a glug or two of olive oil slowly until it comes together. This will keep in the fridge for about five days.
Serve with the mixed leaves and dress with the basil oil.