Combine the water, oil, maple syrup, and vanilla in a large bowl. Mix well.
Sift together the carob powder, flour, and baking powder. Add the flour mixture to the liquid mixture and mix until just blended. Don't overmix. Fold in the chocolate or carob chips and the walnuts, if desired.
Drop by the spoonful onto an oiled baking sheet. Leave some space between the cookies for them to expand. Bake at 350°F for 8 - 10 minutes. Cool on the baking sheets.