Heat the oven to 425˚F. Lightly oil two large sheet pans.
Peel the carrots, if needed then halve them lengthwise. Cut into quarters if carrots are fat.
Place the carrots, honey, olive oil, coriander seeds, cumin seeds, thyme (if using), a teaspoon of salt and plenty of black pepper in a large bowl or zippered bag. Mix until the carrots are well coated, then spread out over the prepared pans.
Roast for about 40 minutes, flipping carrots several times, until tender, golden and glazed.
Meanwhile, make the sauce. In a medium bowl, whisk together the tahini, yoghurt, lemon juice, garlic and an eighth of a teaspoon of salt.
Once the carrots are done, place on individual plates while still warm or at room temperature. Top with a spoonful of sauce and scatter over the chopped coriander.
Notes
This recipe works better with large, more squat carrots versus long, thin ones. Adapted from The Guardian