In a large shallow bowl, whisk together the soy/tamari sauce, lemon juice, chilli sauce and ginger. Marinade the tofu in this sauce for at least one hour.
Add the oil to a wok or a large skillet; cook the onion, garlic, capsicum, broccoli and tofu over high heat, stirring frequently.
Add the snow peas, mushrooms, shallots and marinated tofu.
Allow to cook for just a few more minutes.
Vegetables should be tender but still retaining a little crunch.
Remove from heat and stir through the mint.
Divide into bowls and garnish with mint sprig.