Hum..I am not familiar with the restaurant but I can maybe give you a ballpark guess. As Jigglefree mentioned, it really depends on the size of a "handful. Would you say half a cup or a quarter cup each?
I use feta and balsamic vinegar every day. They are two of my favorites.
Balsamic: If it was just the vinegar with no oil then it is 15 calories per Tbsp. If it is an oil dressing, then it would be 30-40 cals per Tbsp.
Jigglefree mentioned the spinach
Feta: Regular feta is 90 calories per 30 grams which is a little less than 1/4 cup crumbled. light feta is 60-70 calories per 30 grams. A small handful will probably be about a serving and a half or 135 calories where a medium handful could be close to 180. Cheeses can add up fast!
walnuts: 1/4 cup or a small handful is about 170 - 190 calories.
Tangerines are about 28 calories each
A medium apple is about 45 calories.
You can take it from there and decide the amounts that were added to your salad
I hope that is helpful