In a small bowl, whisk together tahini, water, lemon juice, olive oil, garlic, black pepper, and chopped mint until smooth. Add additional water, 1 tablespoon at a time, until the dressing is the consistency you like.
Assemble the salad:
In a large bowl, combine spring mix, arugula, lentils, pistachios, and blueberries. Drizzle the dressing over the salad and gently toss until evenly coated. Divide into 4 serving bowls and serve immediately.
Notes
Use pre-cooked lentils for a quick, no-cook meal The salad is best served fresh, but dressing can be made ahead. Add water slowly to thin tahini dressing. It will thicken as it sits, so you may want to add more later. Leftover dressing can be stored in an airtight container in the fridge for up to 3 days. If you are nut-free, swap the pistachios out for sesame seeds or sunflower seeds.If you prefer to cook your own lentils: Cooking dried lentils on the stove is nice and easy. Give the lentils a rinse in water. Rinsing them removes and dust and debris, it also helps reduce those carbohydrates that might cause gas. Then, in a large pot, for each pound of dried lentils (about 2 cups dried lentils), add 6 to 8 cups hot water. Simmer gently with lid tilted until desired tenderness is reached, about 15-20 minutes for unsoaked lentils. Drain any excess liquid from the pot.