A controlled release means that you release the pressure in small bursts, stopping if there appears to be any liquid coming out that is not steam. If the soup liquid seems to be spewing out, immediately close the vent back to sealing and let the Instant Pot sit for a few minutes to continue to naturally release, then try to manually release the pressure again. (Opening the valve on your Instant Pot is not the gateway to 3rd-degree burns and explosions - people totally overreact about this. All you need to do is very lightly touch the knob - don't even open it all the way - to let some pressure out. It won't shoot flaming magma into your face or blast a hole through your ceiling. Just touch the knob and let a little steam out - close it if the steam is not just steam. And don't stand or put your face directly above the vent.)