Roast the walnuts in a pan without fat until golden brown. Take out and let cool down. Sort the arugula, wash and drain well. Wash and halve the grapes. Peel and halve onions and cut into fine strips.
Cut the avocados in half lengthwise and remove the core. Remove the flesh from the skin with a spoon, dice it finely and mix with lemon juice.
Mix vinegar, honey and mustard, season with salt and pepper. Fold in the oil. Carefully mix the vinaigrette and prepared salad ingredients together and arrange in a bowl.