Lemony carrot and cabbage add a bright, crisp bite to the garlicky Boursin and creamy avocado in this vegetarian meal.
Using a vegetable peeler or mandoline, shave carrot into ribbons. Toss carrot and cabbage with lemon juice and oil. Season with salt and pepper.
Spread 4 slices of toast with Boursin and shingle with cucumber rounds. Season lightly with salt. Lay slices of avocado on remaining 4 slices of toast; mash lightly with a fork. Season with salt and pepper and drizzle with oil. Layer pea shoots, cabbage, and carrots over avocado. Close sandwiches, slice, and serve.