The appearance of this apple, subdued yellow-green mottled by russet, with a splash of translucent red blush, is not promising.
Belle de Boskoop is a large medium-sized apple with a slight amount of ribbing and a sweet cider aroma.
Light lenticels are not obvious except where russeted over.
Her flesh is a bit yielding, light yellow and halfway between fine and coarse-grained. The flavors are generally pleasant, for there is a decent amount of tartness to balance the pure cane-sugar sweetness.
However, despite a hint of pear, something almost savory, and some lively spicy notes, this apple never really comes together for me. (But, here's another opinion.) I wonder if cooking, or fermentation, unlocks this apple.
This Dutch variety (Boskoop is about 20 miles north of Rotterdam) originated around the middle of the 19th Century. Apples of New York did not like it much, though Yepson is a bit kinder.
Belle's flesh oxidizes very quickly.