Heat The Oil In A Large Skillet Over Medium Heat. Cook The Pumpkin In The Heated Oil 2 To 3 Minutes. Stir In The Vegetable Stock, Cumin, Salt, And Pepper. Cook Until The Pumpkin Cubes Are Easily Pierced Through With A Fork, 5 To 7 Minutes. Fill Warm Tortillas With Pumpkin; Top With Tomato, Onion, Avocado, And Cilantro As Desired.