Preheat oven to 350°.
Put the seasoning paste, tomatoes, and orange juice in a blender and blend until smooth.
Put the onions and potatoes in an ovenproof casserole dish.
Add the seasoning mixture, oil, and salt.
Turn to coat the vegetables.
Cover and bake about 20 minutes.
Remove the cover and continue to cook until the liquid is absorbed and the vegetables are browned and tender, 25 to 30 minutes.