1. Bring a small pot of water to boil. Boil the peas until they're bright, sweet, and tender (3-5 minutes). Drain them and immediately plunge them into a bowl of ice water to arrest the cooking and keep the color bold. Drain them and transfer them to a food processor. Pulse in the mint, salt, and lemon juice. With the motor running, pour the oil into the food processor in a thin stream. Stop the motor and mix everything up. You want a mixture that's not quite pureed, but also fairly uniform. Continue to pulse as needed, until you're pleased with how it looks. Set the minted peas aside.
2. To prepare the cashew cheese, place the cashews in a food processor or high speed blender along with the lemon, sea salt, and pepper. Blend the cashews until they've taken on the texture of a spreadable cheese/thick hummus. Add water as needed (a third cup or half cup is normal). Continue blending, stopping occasionally to scrape the machine down, till the cashew cheese is very smooth. Transfer it to a container and mix in the chives, if desired.
3. Toast the bread. Cut each slice into four pieces. Top each with a heaping tablespoon of the pea mixture, and then a small dollop of the cashew cheese. Serve, garnished with a sprig of mint if desired.