Grilled Fish Kebabs with Garlic and Herbs

Name: Grilled Fish Kebabs with Garlic and Herbs
Ingredients: ½ cup cilantro leaves, finely chopped; 6 garlic cloves, finely chopped; 1 Tbsp. kosher salt; 1 tsp. freshly ground black pepper; 1 Tbsp. ground coriander; 1 tsp. ground cumin; ½ tsp. ground fennel seed (optional); 2½ lb. firm, thick fish fillets such as swordfish, striped bass, or halibut, cut into 1-by-2-in. cubes; ½ cup extra-virgin olive oil; ½ cup fresh lemon juice; 1 Tbsp. fresh dill, finely chopped; Arugula or grilled fresh pineapple rings, for serving (optional); Vegetable oil, for brushing; 40 red or yellow cherry tomatoes; Lemon slices, for serving (optional)