Bring a pot of salted water to a boil, then add the lentils. Cook until just tender, drain, and rinse under cold water to stop the cooking process. Make sure your lentils still have a crunch to them, or they will disintegrate in the salad and it won’t look nice.
Place a large skillet over medium-high heat. Add two big drizzles of grapeseed oil to the skillet and add the beans. Sprinkle with some sea salt and let cook, unturned, for about 4 minutes. Stir and turn the beans as much as possible to obtain a nice char on all sides. Cook for a total of 6-7 minutes. Remove from the heat and set aside.
In a small bowl, whisk the red onion, Dijon mustard, maple syrup, grapeseed oil, and tarragon. Season to taste with sea salt and pepper.
In a large salad bowl, place the lentils, the beans, the kale, and the vinaigrette. Mix well until evenly coated. Serve topped with toasted seeds and toasted pistachios. Bon appétit!