Mince the garlic clove. In a bowl, combine 3 tablespoons olive oil, juice from roughly half a lemon, minced garlic, 1 teaspoon thyme, 1 teaspoon oregano, and 1 teaspoon rosemary. Season with salt and pepper. Cover and refrigerate for 24 hours.
Heat a large pan over medium-high heat and add the herb-infused oil mixture.
Add the bell pepper cubes, onion pieces, and mushroom halves. Fry for 3-4 minutes, stirring occasionally, until the vegetables soften slightly.
Add the halloumi cheese cubes and fry for another 2-3 minutes until the cheese is golden and slightly crispy.
Remove from heat. Top with finely chopped parsley and a squeeze of fresh lemon juice. Serve warm.