Preheat the oven to 200C/400F/Gas Mark 6.
Drizzle 2 tbsps of the olive oil over the spring onions and arrange in a single layer on a baking tray. Cook for 30 mins, until lightly charred.
Meanwhile, in a bowl, combine the ricotta with the garlic, half the dill (roughly chopped), a pinch of salt, chilli flakes, and the lemon zest and most of the juice.
Unroll the puff pastry sheet on to a chopping board and lightly score into it, a thumb’s width from the edge, all the way around. Spread the ricotta mixture over the rectangle in the centre. Set aside in the fridge until your spring onions are ready for it.
Take the spring onions from the oven and slice the roots off. Line a baking sheet with greaseproof paper, assemble the spring onions in a tight line, and flip the pastry over them, ricotta side down.
Return to the oven and bake for 25 mins, until the pastry is risen, crisp, and a deep golden colour. Let it cool for 10 mins, before placing a chopping board over the pastry, then flipping it over.
Meanwhile, cook the peas for a couple of minutes in a pan of boiling water, then cool them quickly by straining them and dropping them into iced water (or running cold tap water over them). Leave them to drain.
Whisk the mustard with the last of the lemon juice and the remaining olive oil. When you’re ready to serve, toss the peas, pea shoots and remaining fronds of dill through the dressing.
Top the tart with the dressed peas and pea shoots, and serve warm.
