Mix the sauce ingredients in the mixer. Cut the bell pepper and carrot into strips. Slice the spring onions and set aside some of the green part as a garnish. Cook the udon noodles al dente, drain and set aside.
Heat some oil in a pan and fry the vegetables. Lightly salt and pepper the vegetables. Add the pasta and sauce, mix well and continue cooking until the sauce thickens.
Divide the dish between 2 bowls and garnish with the green part of the spring onions.