Spread the hazelnuts out on a small cookie sheet and roast for 10-15 minutes, tossing occasionally to prevent burning. When toasted and blistery, remove them from the oven and pour them onto a clean kitchen towel. Wrap them and allow them to steam for a minute, then rub them in the kitchen towel to remove the skins (note, not all of the peel will come off).
In a small bowl, combine the olive oil, vinegar, honey, salt and pepper and stir until the salt is dissolved.Place the watercress, red onion, strawberries and hazelnuts in a bowl, pour the dressing over and toss to coat. Serve immediately.