For 19 years, Kostas Fostieris’s Greek Deli in the Golden Triangle area has nourished some of downtown’s hungriest hotshots. Nestled alongside power-lunch spot Smith & Wollensky, the deli’s giant $7.50 gyro is a much better bang for your buck than the $50 filet next door. They’re only open for lunch, and it’s kind of a shame when a spanakopita craving strikes at 5 p.m., but it just means the midday.....