Boil the potatoes with 1 tablespoon salt in the water for about 15-20 minutes or until tender. Drain and then put them under cold running water to stop them from cooking . Dry, and cool to room temperature. Put into a roomy bowl.
Next cut the onion into 1 inch wide, 1 layer thick square pieces. Put onion into the bowl with the potatoes.
Cut the cheese into 1 inch x 1 inch cubes. Put this into bowl with the cool potatoes.
Now it is time to make the marinade.
In a small bowl, put the finely chopped herbs and 2 garlic cloves minced along with ½ the zest of the lemon. Mix in ½ cup oil and 2 tbsp. lemon juice. Season with ¼ teaspoon pepper. Pour the mixture over the potatoes, cheese and onion. Mix thoroughly but carefully so as not to damage anything. Cover and refrigerate for up to 24 hours.
About ½ hour before cooking, You need to marinate the shrimp. Combine your remaining finely minced garlic cloves, the remainder of the lemon zest, and the remaining ¼ cup olive oil and place into a bowl that will comfortably hold the shrimp. Stir until blended. Add shrimp and gently mix until the shrimp is coated. Cover and put in your fridge.
As you put the shrimp in the fridge take the potatoes out to start warming to room temperature. Take 10 wood skewers and soak them in water or use metal ones.
Prepare a baking sheet with tinfoil and a rack lightly coated in cooking spray. Set aside.
When you are ready to cook, preheat your oven to broil. Take a skewer and thread a potato, then a shrimp, onion, a cube of cheese, tomato and repeat the sequence again ending with a potato. Place on your prepared rack and baking sheet. Repeat for the other kebabs.
Once your oven is hot put in the kebabs, on the second highest or highest rack, depending on your oven. Cook kebabs about 3 minutes per side or until shrimp is cooked.
Your goal is to cook the shrimp until they are pink or in a perfect C shape. If the are straight they are usually undercooked. If they form a ring or O they are overcooked.
To serve: On each plate, put a bed of lettuce, put a kebab on top and sprinkle the remaining marinade from the vegetables on top as a dressing, or make extra if you need to. I usually don't. Sprinkle with some freshly chopped herbs if desired. Enjoy!