Grilling: Pork Souvlaki with Pita and Tzatziki

1/2 cup olive oil

1 small red onion, finely chopped

2 garlic cloves, minced

4 tablespoons fresh lemon juice

2 tablespoons red wine vinegar

2 teaspoons Greek oregano

Salt and Pepper

For the Tzatziki

2 cups of Greek yogurt

1 English cucumber, peeled and grated

4 cloves of garlic, minced

2 tablespoons lemon juice

2 tablespoons extra-virgin olive oil

1 1/2 lbs pork loin, trimmed of silver skin and excess fat, cut into 1-inch cubes

Wooden skewers, soaked in water for 30 minutes before use

Pocketless Pita