Add the sweet potatoes, bell peppers and onions to a large bowl, toss with the olive oil, then add the za’atar, paprika and cayenne pepper and toss until all of the vegetables are coated in the seasoning.
Arrange the vegetables in an even layer on a foil-lined baking sheet.
Place in the oven to roast for 15-20 minutes, or until the sweet potatoes are fork tender.
Divide the cooked quinoa between four bowls.
Add the roasted vegetables, spinach, cherry tomatoes and cucumber.
Top with the lemon tahini dressing.
The sweet potatoes can be roasted peeled or unpeeled, it's really a personal preference. If roasting them with the skins on, be sure to scrub the sweet potatoes clean before dicing and roasting them.