In a small bowl, combine the yogurt, Pure Lemon Paste, red onion, vinegar, salt, and pepper. Whisk until smooth. Add milk, about a teaspoon at a time, until the desired consistency is achieved. For best flavor, prepare and refrigerate for at least 1 hour prior to serving.
Preheat grill or grill pan to medium-high heat.
In a medium pot, bring water to a simmer. Add the quinoa, cover and turn the heat to low. Cook until the quinoa is tender, about 10-15 minutes. Remove from heat and set aside to cool slightly.
In a large bowl, add zucchini, squash and bell pepper with 2 tablespoons of olive oil, salt and pepper and toss to coat. Place zucchini, squash and scallions on the grill and grill for 3 minutes or until golden. Flip and grill the other side until golden and tender about 3 minutes.
Drizzle the halloumi slices with the remaining 1 tablespoon oil and add to the grill in a single layer. Cook for 2 minutes each side or until golden and charred.
In a large bowl add the cooked quinoa and grilled vegetables and mix to combine. Add the dressing and toss. Serve on a platter with halloumi.
