Wash and prep all vegetables. Slice the cherry tomatoes in half, dice the avocado, thinly slice the bell peppers and cucumber, and trim the green beans and snap peas.
Blanch the green beans in boiling water for 2-3 minutes until tender-crisp, then immediately transfer to an ice bath to cool. Drain and set aside.
Pat each slice of halloumi cheese completely dry with a paper towel to ensure a crispy sear.
Heat a grill pan or non-stick skillet over medium-high heat. Brush the halloumi slices lightly with 1 tablespoon of olive oil and grill for 2-3 minutes per side until golden brown grill marks appear.
In a large serving bowl, combine the arugula, cherry tomatoes, bell peppers, cucumber, snap peas, and cooled green beans.
Whisk together the remaining 2 tablespoons of olive oil and the lemon juice to create a simple dressing. Drizzle over the vegetables and toss to coat evenly.
Top the dressed salad with the diced avocado and the warm grilled halloumi slices. Serve immediately while the cheese is still soft and crisp.