Snap the ends off the asparagus where they naturally break. Trim both ends off the radishes and chop in halves or quarters, depending on the size. Put all on a baking sheet and toss with the 1tbsp oil. Sprinkle with a little salt, if using. Roast for 15-20 minutes until vegetables are tender and lightly brown. Set aside to cool then cut the asparagus into bite-size lengths.
Meanwhile, cook the farro according to package instructions (typically simmered in 1 ½ cups of water for 15 minutes until just tender). Add the peas for 1-2 minutes at the end of cooking the farro to lightly cook. Drain and allow to cool.
Mix together the oil, lemon and tahini for the dressing and stir through the farro. Thinly slice the mint leaves and stir them through the farro along with the vegetables and serve or refrigerate until needed. You can serve room temperature or chilled.
Notes
This salad also works well with arugula/rocket mixed in - for the quantity here, add around 3 handfuls, a squeeze more lemon juice and optionally a little more oil. It will then serve another 1-2 more servings.