Finely chop the spring onions, separating whites and greens. Slice the cucumber lengthways, scoop out the watery flesh and finely dice. Mince the garlic and ginger.
Heat a frying pan over medium heat with the sesame oil. Add the spring onion whites, garlic, ginger and chilli oil and toast for 1 minute until fragrant. Add the sugar and soy sauce and simmer for 2 minutes until slightly thickened. Remove from the heat and stir through the spring onion greens and sesame seeds.
Drain the tofu and pat dry with kitchen paper. Transfer to a plate and slice. Spoon over the chilli sauce and finish with the diced cucumber and crispy onions.
