Grilled Tuna Kebabs

1. Stage

Cut into bite-sized pieces: Cut all the fish and veggies into similar-sized pieces; this helps everything lay flat when it is on the grill.

2. Stage

Marinate the fish and vegetables: To make the marinade, purée the onion, rosemary, garlic, salt and pepper in a food processor. Drizzle in the olive oil while puréeing, continue to purée until smooth, about 1-2 minutes. Coat the fish and veggies in the marinade. Set in the fridge for at least an hour and up to overnight.

3. Stage

Thread onto skewers: When skewering the fish and vegetables, pierce the fish against the grain, and select pieces of veggies that are close to the same size as your fish. This is important, because if the pieces are different widths, some things will be charred and others undercooked. You also want to be careful when loading up the skewers; it's easy to stab yourself by accident! Alternate pieces of fish with pieces of various veggies, leaving a little space between everything. Don’t crowd the skewer, or the parts that are touching will cook too slowly. Note that by threading the skewers with assorted veggies and fish, some things will be cooked more or less than others, as some things take longer to cook than others. If you want all of your items to be cooked perfectly, use a separate skewer for the onions, one for the tuna, one for the bell peppers, etc. Put the onions and bell peppers down first because they take longer to cook.

4. Stage

Grill on high, direct heat: Prepare the grill for high, direct heat. Clean the grates and wipe them down with a paper towel that has been dipped in vegetable oil. Lay the skewers on the grill. Don't move them until the fish pieces are well browned on one side, about 3-6 minutes. Then using tongs, carefully turn the skewers over and cook them until they are seared on the other side. Serve hot or at room temperature. Drizzle with lemon juice or serve with lemon wedges.