In a medium saucepan, combine peanut butter, red curry paste, kecap manis, sambal oelek, salt, and minced garlic. Pour in coconut milk and water. Simmer for about 5 minutes, stirring constantly until thickened.

Bring a large pot of salted water to a boil and add potato cubes. Cook for 5 minutes, transfer to a colander. Add beansprouts to boiling water and blanch for 3 minutes, followed by spinach until just wilted, about 1 minute. Drain and set aside.

Heat vegetable oil in a skillet. Slice tempeh into bite-sized pieces and fry for about 5-7 minutes until golden brown. Drain on paper towels.

On a serving platter, arrange blanched vegetables, cucumber, and halved eggs. Drizzle peanut sauce over the top and sprinkle with chopped peanuts and red chili.

Serve Gado Gado with a bowl of crispy prawn crackers.