1 tablespoon plus 1 teaspoon canola oil, divided
1 tablespoon ground cumin
1 teaspoon kosher salt, divided
3/4 teaspoon freshly ground pepper
1 16- to 18-ounce tube prepared plain polenta
1 pound boneless, skinless chicken breast, trimmed
2 nectarines, halved and pitted
1 pint blackberries, coarsely chopped
2 tablespoons chopped fresh cilantro
1 tablespoon lime juice
Hot sauce, to taste
Preheat grill to medium-high.
Combine 1 tablespoon oil, cumin, 3/4 teaspoon salt and pepper in a small bowl. Rub 1 teaspoon of the mixture all over polenta. Rub the rest into both sides of chicken. Cut the polenta crosswise into 8 slices. Rub the cut sides of nectarine halves with the remaining 1 teaspoon oil.
Oil the grill rack (see Tip). Place the chicken, polenta slices and nectarines on the grill. Grill the polenta until hot and slightly charred, 3 to 4 minutes per side. Transfer to a clean plate; tent with foil to keep warm. Grill the nectarines, turning occasionally, until tender, 6 to 8 minutes total. Grill the chicken, until cooked through and no longer pink in the middle, 6 to 8 minutes per side. Transfer the chicken and nectarines to a cutting board. Coarsely chop the nectarines. Let the chicken rest for 5 minutes, then thinly slice.
While the chicken rests, combine the chopped nectarines, blackberries, cilantro, lime juice, hot sauce and the remaining 1/4 teaspoon salt in a medium bowl. Layer the polenta, chicken and fruit salsa on 4 plates and serve.