Mounting refers to mixing ingredients until smooth and even.
To mount a cheese sauce, add chopped herbs, salt, pepper and olive oil. Whisk until you reach the creaminess desired, then stir in the cheese.
To mount risotto, add butter once you are done cooking the rice and have taken it off the heat. Stir until you reach the desired thickness. You can also add chopped parsley and grated Parmigiano Reggiano.