1 large sweet potato (about 12 oz.), peeled, sliced lengthwise into ¼“–½”-thick planks
1 tsp. ancho chile powder
½ tsp. ground cumin
3 Tbsp. extra-virgin olive oil, plus more for drizzling
Kosher salt, freshly ground pepper
1 medium beet, peeled, cut into thin matchsticks or grated on the large holes of a box grater
½ small red onion, thinly sliced
3 Tbsp. seasoned rice vinegar (4 parts rice vin., 2 parts sugar, .5 part salt according to ATK)
½ cup mayonnaise
1 large garlic clove, finely grated
1 Tbsp. plus 1 tsp. fresh lemon juice
2 sesame kaiser rolls, split (great on sliced crusty bread too)
1½ cups parsley, mint, and/or cilantro leaves
5 oz. block feta, thinly sliced into planks, divided