This sounds like a recipe for which I was looking and which I had originally found online after someone gave me a small tub of Paradise citron.
I think I finally found the recipe. It's on cooks.com and it's called Christmas coookies (German) and it does use a lot of eggs and no shortening! so it may be very similar to your mother's.
Here is the link. http://www.cooks.com/recipe/2v4742rl/christmas-cookies-german.html
Here is the recipe:
CHRISTMAS COOKIES (GERMAN)
Printed from COOKS.COM
4 cups sugar
4 oz. chopped citron
4 oz. blanched almonds
grated rind of 2 lemons
9 cups flour
1/2 tsp. ground cloves
2 tsp. nutmeg
1/4 tsp. black pepper
Beat 8 eggs. Add 4 cups sugar, beat until smooth, about 15 minutes. Add
4 ounces chopped citron, 4 ounces blanched almonds, (which have been
coarsely chopped) and the grated rind of 2 lemons.
Sift together 9 cups flour, add 1/2 tsp. ground cloves, 2 tsp. nutmeg, and
1/4 tsp. black pepper to flour and sift again. Add to the first mixture.
Roll out dough 3/4 inch thick. Cut into small rounds 1-inch in diameter.
Before baking, turn each cookie upside down, put a drop of water on
each and bake at 350°F. for 15 minutes.
Let me know if this is it? And how it works out! I might try it today myself, tho' :).