Grilled halloumi cheese on mixed salad

Vinaigrette:

• 125 ml (1/2 cup) olive oil
• 45 ml (3 tbsp) lemon juice, freshly squeezed
• 15 ml (1 tbsp) garlic cloves, peeled, degermed and minced
• 5 ml (1 tsp) dried oregano
• 1 ml (1/4 tsp) Espelette pepper
• 1 ml (1/4 tsp) sea salt
• Freshly ground black pepper

Salad:

• 1/2 romaine lettuce, washed and torn into medium-large pieces
• 1/2  iceberg lettuce, torn into medium-large pieces
• 1/2 English cucumber, washed, seeded, cut into 2 cm (3/4 in.) dice
• 2 ripe tomatoes, each cut into 8 pieces (4 quarters cut in 2)
• 1 small red onion, peeled and thinly sliced
• 180 ml (3/4 cup) black olives, pitted

Grilled cheese:

• 500 g (1 lb) halloumi cheese
• 60 ml (1/4 cup) olive oil
• 30 ml (2 tbsp) fresh mint, chopped