Running executables with arguments from a Jenkinsfile (using bat - under Windows) - command-line

Question

I have read multiple threads and I still cannot figure out how to get my Jenkinsfile to run some applications such as NuGet.exe or devenc.com.
Here is what I have so far as a Jenkins file:
pipeline {
agent any
options {
timestamps ()
skipStagesAfterUnstable()
}
environment {
solutionTarget = "${env.WORKSPACE}\\src\\MySolution.sln"
}
stages {
stage('Build Solution') {
steps {
dir ("${env.workspace}") {
script {
echo "Assumes nuget.exe was downloaded and placed under ${env.NUGET_EXE_PATH}"
echo 'Restore NuGet packages'
""%NUGET_EXE_PATH%" restore %solutionTarget%"
echo 'Build solution'
""%DEVENV_COM_PATH%" %solutionTarget% /build release|x86"
}
}
}
}
}
}
In this example, I get the following error:
hudson.remoting.ProxyException: groovy.lang.MissingMethodException: No signature of method: java.lang.String.mod() is applicable for argument types: (java.lang.String) values: [C:\Program Files (x86)\NuGet\nuget.exe]
Note that a declarative checkout is in place, although not visible from the Jenkinsfile:
I have also tried to use a function to run those cmds, but without success either:
def cmd_exec(command) {
return bat(returnStdout: true, script: "${command}").trim()
}
Any tip would be highly appreciated.