Soak sunflower seeds overnight or all day in pure water with 2 tablespoons of sea salt.
Drain and rinse sunflower seeds. Remove about 1 cup / 135g of the soaked seeds and place in a blender with 1 cup / 250ml water. Blend on high until completely smooth. Set aside.
Melt coconut oil in a large stockpot. Add onions and sea salt, stir to coat and cook over medium-high heat until translucent, about 5-7 minutes. Add garlic and cook 2 minutes, then add sunflower seeds and about 2 cups of the broth. Bring to a simmer and cook covered for 20-30 minutes, depending on the size of your seeds, adding more broth as needed. When cooked the seeds should be al dente: tender with only the slightest crunch still left in them. If there seems to be a lot of liquid left in the pot, let it simmer uncovered for about 5 minutes to evaporate the excess. Add the sunflower cream from the blender and stir to combine, and heat gently. Season to taste. Remove from heat and fold in a few generous handfuls of watercress.
Blanch the vegetables in the same pot of salted water for approximately the time indicated, testing as you go. Do not overcook!
To serve, place about a quarter of the risotto on each plate, then top with the vegetables. Drizzle with olive oil, lemon juice and a sprinkling of flaky sea salt. Top with extra watercress and enjoy warm.