Remove skin from the watermelon, taking off any green and white areas. Cut the red flesh of the watermelon into bite-sized dice or alternatively cut into wedges. Remove any obvious seeds. Place watermelon pieces in a bowl.
Remove the middle stem from the mint leaves then finely shred the leaves. Add to the bowl with the watermelon. Whisk together the olive oil, lemon juice, honey and a little salt and pepper. Drizzle over the watermelon and gently stir to mix and coat with the dressing and mint. Set aside for around 10 minutes to marinade, or at least as you cook the halloumi.
To make salad
Cut the halloumi into slices - they should be relatively thin but not overly so. Fry on both sides in a dry skillet/frying pan until golden on both sides, a couple minutes each side. Don't worry if they split, you can cut up the pieces after a little along wherever they separate. And even if they don't, you may well want to cut the slices into smaller chunks to be closer in size to the watermelon pieces.
Place the arugula/rocket in the bottom of your serving plate(s). Top with the watermelon and drizzle over any extra marinade/dressing. Add the slices of halloumi - you can tuck them between the watermelon, as makes sense - and drizzle over a little more olive oil, as needed/to taste before serving.