Put your mini mash in a nylon mesh paint strainer bag, secure it with a thick rubber band or twist-tie, and mash in a smaller covered pot at about 1.3-1.5 liters water at about 147-155 F degrees (depending on recipe) per lb. of grain. The smaller volume will allow you to use a smaller kettle to mash in while your main volume of water is heating up in the larger kettle.
Lower mash temp. range for more alcohol and less body. Higher mash temp. range for less alcohol and more body. If you want to level out at about 151 F, then I recommend mashing your grains at 147-148 F since the grain used to make the Extract was probably mashed around 152-154 F by the maltster.
While your minimash is happening, simultaneously heat your main volume of plain water to 170 F-ish in a separate larger kettle. After the minimash, dunk sparge the grain bag into the 170 F-ish kettle to rinse the sugars and mashout. Afterward, let drip drain into a bowl and proceed with the rest of your recipe.