Preheat oven to 180C. Combine yeast, a pinch of flour and 125ml lukewarm water in a bowl, stir to dissolve yeast and set aside until foamy(5-7 minutes). Combine remaining flour, fennel seeds and 1 tsp sea salt flakes in a large bowl. Make a well in the centre, pour in yeast mixture and olive oil, mix to form a dough, turn onto a lightly floured surface and knead until smooth (5-7 minutes). Place in a large lightly oiled bowl, cover and set aside until doubled in size (50 minutes-1 hour). Divide dough into walnut-sized pieces, then stretch and roll each piece on a lightly floured work surface to form a thin cylinder about 25cm long. Place on baking paper-lined oven trays, scatter with sea salt and cook in batches until golden and crisp (10-12 minutes), then cool completely. Makes about 35.
For marinated zucchini, heat a chargrill on high heat, brush zucchini with a little extra-virgin olive oil, and grill in batches, turning once, until cooked through (2-3 minutes). Combine oregano, garlic, lemon rind and remaining oil in a bowl and pour over zucchini. Season to taste and serve with grissini.