Start a grill over medium-high heat. Rub the fennel halves with some olive oil and season liberally with sea salt and pepper. Place the fennel cut-side down on the hot grill and cook, covered, until deep char marks appear on the flat side of the fennel halves. Turn and repeat the process on the other side. You can turn again and cook some more if your grill isn’t too hot. If the grill is too hot, transfer the fennel halves to the non heated zone of your grill (or on the little warming shelf many grills have). Cover and let cook some more until you obtain a very cooked, sweet tasting, and aromatic fennel.
While the fennel is cooking, make the vinaigrette by combining the orange juice, the orange zest, the shallot, Dijon, olive oil, maple syrup, and salt and pepper. Whisk until smooth, taste and adjust seasonings.
Toss the kale in a large bowl with a little bit of the vinaigrette and massage with your hands for one minute. Plate and set aside. Once the fennel is cooked, transfer to a cutting board and slice thin, discarding the cores. Transfer to the plate on top of the kale. Top with the orange supremes, some vinaigrette, and the fennel fronds.