Preheat your oven to 425°F / 220°C and line a rimmed baking sheet with parchment paper, Silpat®️, or foil.
Cut the carrots in half crosswise. Cut the top half of each carrot in half lengthwise. Slice all the carrots crosswise, on the diagonal, into 2-inch / 5cm pieces.
In a large mixing bowl, toss the carrots with the avocado oil, cumin, and chili powder. Season the carrots well with salt and freshly ground black pepper. Arrange the carrots on the prepared baking sheet. Roast the carrots, stirring once halfway through cooking, until tender and light brown, 30 to 40 minutes.
Bring a medium pot of water to boil. Add the lentils to the boiling water. Boil for 30-35 minutes, or until the lentils are tender, yet firm (not mushy). Drain the lentils thoroughly through a fine sieve.
Transfer the arugula, roasted carrots, and cooked lentils to a large mixing bowl. Pour a half cup (120ml) of the orange miso vinaigrette over the mixture. Toss the ingredients together well. Add additional vinaigrette by the tablespoon as needed, until the ingredients are dressed to your liking. Taste the salad and season as needed with salt and freshly ground black pepper.
Divide the salad onto plates or into bowls and top each portion with a tablespoon each of sunflower seeds or pepitas. Enjoy. The salad can be stored in an airtight container or containers in the fridge for up to 3 days.