Cut the red potatoes into 1-inch chunks and slice the smoked sausage into 1-inch rounds. Husk the corn and cut into 3-inch pieces. Peel and quarter the large onion, then slice the lemon into 1/2-inch rounds. Mince the garlic and peel and devein the shrimp, leaving tails intact. Having everything prepped and ready (mise en place) makes the cooking process seamless and ensures even cooking throughout.

Add the water to your crockpot first, then add the prepared potatoes, smoked sausage, corn, onion, lemon slices, minced garlic, Old Bay seasoning, and bay leaf. Stir everything together well to distribute the seasoning evenly throughout the liquid. The potatoes need the most cooking time, so starting them first ensures they'll be tender by the time everything else is ready.

Cover the crockpot and cook on HIGH for 2-3 hours or on LOW for 4-6 hours, depending on your time availability. The potatoes are done when they're fork-tender but still hold their shape. I like to check them after 2 hours on HIGH just to gauge doneness—this helps me know exactly when to add the shrimp for perfect timing.

Once the potatoes are tender, add the prepared shrimp from Step 1 to the crockpot and stir gently to combine. Cook uncovered for 10 minutes until the shrimp turn pink and opaque throughout. Don't overcook the shrimp or they'll become tough—10 minutes is perfect for large shrimp in the hot broth.

Using a slotted spoon or small colander, carefully transfer all the solids from the crockpot to a large serving platter or individual bowls. You can discard the bay leaf and lemon slices, or leave them for flavor. Pour a little of the cooking liquid over the seafood boil if desired, then garnish with fresh chopped parsley and serve immediately.