Slice firm tofu into cubes the size of croutons and pat dry with paper towel. Toss tofu in cornstarch until each cube is fully coated.
In a large wok over medium high heat add vegetable oil until it is 2-3 inches from the bottom of the pan. Gently drop tofu cubes into the bubbling oil and cook for 4-5 minutes until golden brown and crispy. Remove deep fried tofu with a metal slotted spoon and let cool on a paper towel.
In a large bowl combine cabbage, jicama, cucumber, orange, grapefruit, bell pepper, red onion, and cilantro. Cover and chill up to 4 hours.
Prepare Singapore Salad dressing by whisking together in a small bowl peanut/sesame oil, rice vinegar, mirin, fish sauce, sugar, lime juice, ginger, sesame seed and soy sauce.
Pour dressing over salad and toss lightly to coat. Sprinkle with peanuts.