Clean the sugar snaps by cutting slightly at the top with a pairing knife and pulling to remove the stringy part of the vegetable. Do this on both sides and if it doesn't come off easily don't worry about it.
Click off the leaves of the gem lettuce and cut into quarters. Soak in ice water for at least 5 minutes.
Get a large pot of water boiling and salt it heavily. It should taste as salty as the sea. Get another ice bath ready. Blanch the vegetables for 1 minute.
Refresh in ice water and stir to cool them quickly.
Dry off the blanched vegetables on a towel.
Place everything in a big bowl and season lightly with salt and pepper. Add the dressing and carefully mix. I use my hands to mix but you can use a spoon if you'd like.
Serve on a big plate to share or plate separately.
Blanching the peas in salted, boiling water and refreshing them in ice water helps to keep the veggies bright green.