If using wooden skewers, you will need to soak the skewers first because it will take the longest. Submerge wooden skewers in water and let them soak for about 20-30 minutes.
Cut salmon fillets into cubes that are about 1.5-2 inches.
In a mixing bowl, combine freshly squeezed lemon juice, oil, pressed garlic, herbs, salt, and pepper. Mix to well and add salmon pieces. Gently toss salmon to coat them in the marinade evenly.
Let salmon sit there for a few minutes, while you prepare veggies and preheat the grill.
Slice zucchini and summer squash widthwise, to get circles, but not too thin. Depending on how soft or crunchy you like your vegetables, you can slice them thinner to cook faster or thicker to cook less.
Season zucchini and squash with garlic powder, salt, and pepper on both sides.
Slice lemon into thin slices.
Prepare the grill:
Prepare the charcoal for the grill until ashed over and make sure to clean the grill grate. Set the coals to the lowest level away from the grill grate because you will be cooking salmon over direct heat. (For gas grill, set the temperature at medium-high (400°-425°) direct heat.)
Make sure to clean the grill grate before placing salmon kebabs on it.
Grilling Salmon Kebabs:
Skewer pieces of salmon, vegetables, and lemon slices onto each skewer. You can alternate them as you wish and try to fit 2-4 pieces of salmon onto each skewer, along with vegetables and lemon. It will depend on the length of skewers and how you want to serve them.
Brush the skewers with the marinade leftover in the bowl and place them onto the grill grate, directly over the coals.
Grill salmon kebabs for about 4 minutes per side, depending on how thick your salmon filets were. (If they were thin filets, keep it around 3 minutes per side, if they were thick salmon filets, you may need to cook them for up to 5 minutes per side. Total cook time will be 12-20 minutes.)