Bring potatoes to a boil in a pot of salted water. Cook until knife-tender, about 6 minutes. Drain and set aside.
Heat 2 tablespoons oil in a large saucepan over medium-high heat. Add cumin and cook until fragrant, about 30 seconds. Add potatoes and cook, stirring occasionally, until golden, 5 to 7 minutes. Transfer to a bowl; set aside.
Heat remaining oil over medium heat. Cook jalapeno, scallions, tomatoes, beans, yeast, and tempeh, stirring, until tomatoes begin to break down, 5 to 7 minutes. Add potatoes and cook until heated
through. Remove pan from heat and gently stir in avocado. Season with salt and pepper. Garnish with reserved scallion.