- Grill the bacon under a hot grill until crispy, then set aside.
- While the bacon is cooking, place the green beans in a pan of boiling water and blanch for 1-2 minutes until they’re bright green and tender but still crisp. Tip the beans into a colander, rinse under cold water to cool, then drain.
- Heat a non-stick frying pan. When hot, add the mackerel fillets and fry for a few minutes, turning half way through, until the fish is thoroughly heated. Remove from the pan and keep warm.
- Give the pan a wipe with kitchen paper, add the olive oil and return to the heat. Add the red onion and cook gently for 1 minute, making sure it doesn’t brown. Add the tomatoes, green beans and mustard dressing and season with black pepper. Toss well to coat the vegetables in the dressing and warm through.
- Place the toasted bread on two serving plates. Divide the vegetable mixture between the two plates, spooning it over the toast. Lay over the mackerel fillets and top with the crispy bacon.
Tip: For an extra twist, you could cook the bloomer as French toast: soak the bread in 2 beaten eggs, heat a little oil in a frying pan and add the egg-soaked bread, turning once and cooking until golden on both sides.