Strain, and press nothing through

What you push through the sieve is exactly what you spent two hours removing from the sauce.

Let it fall through on its own weight first. Most of the sauce comes through in the first minute without help.

Then tap the rim of the sieve, do not press the solids. Tapping shakes the liquid loose; pressing forces fat, starch and vegetable pulp back in and turns a clear sauce cloudy.

For the finest finish, strain twice: once through a conical sieve, then through muslin. Once is enough for a family dinner and twice is what makes a sauce look bought.