Heat 1/4 cup (or less) of the oil in a large skillet over medium-high heat. Add the onion and salt and saute, stirring occasionally, until the onion begins to soften, about 2 minutes. Add the garlic and ginger and cook, stirring constantly, for 2 minutes more. Add the tempeh, eggplant, and 3 tablespoons of the tamari and cook, stirring occasionally, until the eggplant softens, 10 to 15 minutes. Remove from the heat and set aside.

Heat the remaining 2 tablespoons oil and the remaining 1 tablespoon plus 1 teaspoon tamari in a large saucepan over medium heat. Add the orzo and saute until it has absorbed the liquid and begins to stick, about 2 minutes. Add 3 cups boiling water and the miso. Whisk thoroughly until the miso dissolves. Reduce the heat to very low and cook just below a boil, stirring almost constantly, until tender and creamy, 15 to 20 minutes. Stir in more boiling water if the orzo seems too dry. Stir in the eggplant mixture and serve.