This is a hard paste porcelain cider mug, hand painted in such a way so as to be used by a left-handed person. When a mug is painted such that the dominant painting is on the side where the handle is to the right, the mug is for a right handed person. When a mug is painted such that the dominant painting is on the side where the handle points left, then the mug is for a left-handed person.
The porcelain was made by one of the factories in Vienna, Austria, and dates to the end of the 19th century to the beginning of the 20th century, circa 1890 to 1910. The artist's signature is on the front of the mug, towards the bottom, above a cluster of currants, and the signature reads as "Comfort." This specific whiteware was typically used by Bawo & Dotter, a company located in New York who imported hand painted porcelain to the United States; Bawo & Dotter owned a porcelain factory along with a decorating studio in Fishern, Bohemia and another decorating studio in Limoges, until it started production of porcelain in 1896 in Limoges. The company employed artists who hand painted and signed Bohemian, Austrian and Limoges porcelain for import into the United States. Bawo & Dotter eventually became known as Elite Works and then purchased William Guerin in Limoges.
The mug is 5" high and 4 1/8" wide at the mouth.
The ground is shaded and blushed from green-to-yellow-to-orange-to-brown-to blue-to-red. The handle is also shaded. The artist painted clusters of ripe red currants dangling down the sides of the mug, with brown stems and green leaves. The inside of the mug is glazed white.
There are no chips, cracks or crazing. However there is gold wear to the rim of the mouth, and inside the mug at the top, the white glazing is stained a brownish color, either from use by the estate or a by-product of the decorating process. My instincts are because hand painted left-hand mugs are so rare, the staining is caused by use, and that perhaps the mug was used by the estate every morning for a large mug of coffee.
The green underglaze maker's mark is a crown with the words Vienna Austria