1/4 cup olive oil
1/4 cup butter - unsalted
1 small white onion - diced
1/2 cup white wine
6 cups chicken or vegetable stock
1 pound risotto rice (Arborio, Vialone Nano, or Carnaroli)
1 preserved lemon - skin only, finely diced
1/4 cup Parmigiano Reggiano - grated