Bring a large pot of water to the boil and cook the farro until tender (around 20 minutes). Drain, set aside to cool and transfer to a large bowl.
Heat a chargrill pan or barbecue to high and grill the corn until tender and lightly charred, turning occasionally, around 10 minutes. Allow cooling then remove the kernels with a knife and add to the farro.
Warm the olive oil in a large pan over medium heat and fry the zucchini until golden and tender, around 8 minutes. Season with sea salt and transfer to the corn and farro. Add in the pistachios, mint, parsley and zucchini flowers, if using.
For the dressing, whisk the miso paste, olive oil, vinegar and garlic in a bowl until combined. Thin out with a little water if needed, season with sea salt and check for acidity, adding more vinegar if needed. Pour over the salad and mix so that everything is well coated in the dressing and serves.