I am still in the early stages of learning linq and i have a feeling the following projection can be done using the Select() extension method.

Are these two equivalent?

return MetaData.User.Select(Map).SingleOrDefault(dto => dto.Email == email); 

        public UserDTO GetByEmail(string email)
        {
            return Map(MetaData.User.SingleOrDefault(e => e.Email == email));
        }

        private UserDTO Map(UserEntity user)
        {
            if (user == null) return null;

            return new UserDTO(user.UserId, user.Email, user.FirstName, user.LastName, user.Avatar);
        }

You can do the following:

            var q = from c in metaData.Customers
                    select Map(c.CustomerId, c.CompanyName);

        private CustomerDTO Map(string customerId, string country)
        {
            return new CustomerDTO(customerId, country);
        }