Heat the oven to 425ºF.
In a bowl, combine the butternut squash with the squash seasoning blend and 1 to 2 tablespoons oil. Season generously with salt and pepper and toss to coat. Spread the squash on a sheet pan in an even layer. Roast in the oven until browned and tender, 18 to 20 minutes.
While the squash roasts, make the sauce.

• Peel and thinly slice the shallot.
• Coarsely chop the cilantro.
• Strip the basil leaves from the stems; coarsely chop the leaves.
• Cut the lime into wedges.

In a pan over medium heat, warm 1 tablespoon oil until hot but not smoking. Add the shallot and cook until softened, 2 to 3 minutes. Add the pumpkin seed sauce base and ½ cup water (add more water for a thinner sauce). Cook at a gentle simmer until the flavors meld, 2 to 3 minutes. Remove from the heat and stir in half the cilantro and half the basil.

On the stovetop directly over a flame, or in a dry pan over medium heat, warm the tortillas until just pliable and warmed through, about 30 seconds per side.

Transfer the pumpkin seed sauce to individual plates and top with the squash. Garnish with the remaining cilantro and basil, and serve with the yogurt, tortillas, and lime wedges on the side.