Heat milk, cream and 1 tsp sea salt in a saucepan until it reaches 82°C, about 10 minutes, stirring occasionally. Remove from heat and cool to 40°C, about 1 hour.
Mix rennet with ½ cup water. Whisk this into the milk mixture. Allow to sit for at least 30 minutes, until set but still quite soft.
With a wooden spoon, make a cross in the mixture, then slowly stir milk in one direction around edge of pot, so that the curds begin to separate from the whey. Continue to stir gently until you have gathered a large mass of curds. Don’t over-mix it or you will end up with a grainy texture. Rest mixture again for 10 minutes.
Gently spoon the curds into a ricotta basket with a one-litre capacity (the baskets have holes to let the whey continue to drain), or drain through muslin. Continue to drain for at least 2 hours.
Place zucchini in a bowl with 2 tbsp lemon juice, 2 tbsp oil and the chopped chilli. Season with salt and pepper. Marinate for about 10 minutes.
Pod broad beans and peas. Blanch broad beans in boiling salted water for 1 minute. Refresh in iced water, drain, then peel away second skin. Blanch peas for 2 minutes until al dente, then refresh and drain.
Lightly pound peas, beans, mint and ½ tsp salt in a mortar with a pestle. Add pepper and remaining olive oil, then mix. Add this to the zucchini and stir through. Check seasoning.
Spoon ricotta onto a large serving plate. Place snow pea tendrils and spring vegetable mixture over the ricotta. Drizzle with a little more oil, a good grind of pepper and serve immediately with freshly toasted sourdough.