Closely adapted from Gena Hamshaw.
Preheat your oven to 400F. If you're cooking lentils from scratch, mix the dry lentils in a saucepan with enough water to cover them by two inches. Bring to a boil and reduce to a simmer.
Let the lentils simmer for 25 minutes, or until the lentils are still tender but retain their shape and firmness, while you work on prepping the rest of the salad. When the lentils are mostly tender, add a pinch of salt. When they are completely tender, drain and set aside to cool.
Toss the cauliflower florets with the oil, sumac, lemon zest, ground cumin, salt, and black pepper. Spread the veggies onto 2 baking sheets.
Roast the cauliflower for 20-25 minutes, or until the cauliflower is tender and lightly browning. Stir them on the sheet halfway through roasting. Allow the roasted cauliflower to cool to room temperature.
Pour the hot water over the garlic. This will help tone down the harsh effects of the garlic. When the water has cooled to a warmer room temperature, whisk in the tahini, lemon juice, salt, agave or maple syrup and freshly ground black pepper to make the dressing. If it's too thick, add a few extra tablespoons of water. Taste for more lemon juice, agave or maple syrup and salt.
Make sure the carrots are grated.
When the lentils and cauliflower are cool, toss them together with most of the shredded carrots. Toss all of that with the arugula.
Pour the dressing over the whole salad and toss to coat--I found it easiest to use clean hands, as the cookbook suggested. Plate the salads, sprinkling the remaining shredded carrots over each serving.