The phrase "large strainer" refers to a big tool used for separating solid particles from liquid substances by filtering them through small holes or gaps. Full definition
Then I put it in my oven with the light on for 16 hours take out and put in large strainer that I have lined with a very old tea towel. (davidlebovitz.com)
Place large strainer over bowl, and line with triple layer of cheesecloth. (vegetariantimes.com)
Place large strainer over bowl, and line with triple layer of cheesecloth. (vegetariantimes.com)