Grilled Salmon and Polenta with Fennel Salad

Name: Grilled Salmon and Polenta with Fennel Salad
Ingredients: 3 lemons (1 juiced, 2 halved); 1 teaspoon dijon mustard; 2 tablespoons extra-virgin olive oil, plus more for brushing; 1 pint grape or cherry tomatoes, halved; 1 bulb fennel, trimmed, cored and very thinly sliced, plus 1/4 cup chopped fronds; Kosher salt and freshly ground pepper; 4 6-ounce skinless center-cut salmon fillets (preferably wild); 1 teaspoon ground fennel seeds; 1 14-ounce tube prepared polenta, sliced into 8 rounds; 1 cup torn fresh basil