Wash and thoroughly dry the kale, then remove the tough stems and chop the leaves into bite-sized pieces. Place the chopped greens in a large mixing bowl.
Massage the kale with about a teaspoon of lemon juice or a splash of olive oil, squeezing and rubbing the leaves for 2-3 minutes until they become tender, glossy, and slightly darker. This step softens the greens and reduces bitterness.
Bring water to a boil in a small pot. Add the thawed peas and cook for 2-3 minutes until bright green and tender. Drain the peas and rinse with cold water to stop the cooking process, then set aside to cool.
In a small bowl, whisk together the olive oil, Dijon mustard, lemon juice, and a pinch of salt and pepper until well combined and emulsified. Adjust the seasoning to taste.
Add the cooled peas to the massaged kale and pour the dressing over the top. Gently toss everything together until the greens are evenly coated and the peas are distributed throughout.
Sprinkle toasted sunflower seeds over the salad for crunch and visual appeal. Give the salad a final gentle toss to combine all ingredients thoroughly.
Let the salad sit for 5 minutes to allow flavors to meld. Taste and adjust seasoning with more salt, pepper, or lemon juice if desired.
Serve the salad in bowls or on plates, garnished with additional herbs if you like. Enjoy the fresh, crisp, and nourishing flavors of this spring-inspired dish!