Preheat the oven to 220C, fan-forced. Line an oven tray with baking paper. Cut the zucchini into 1.5cm-thick batons. Thinly slice the onion into rounds. Trim the lettuce, then separate the leaves. Thinly slice the tomato. Crush or finely chop the garlic.
Step 2 — Bake zucchini fries
Put the zucchini on the lined tray and drizzle with 2 tsp olive oil. Season with pepper and toss to coat. Bake the zucchini for 10-12 mins until tender and golden. Scatter with 2 tsp Tuscan seasoning and gently toss to coat.
Step 3 — Make patties
Meanwhile, put the beef mince, garlic, remaining Tuscan seasoning and 1 egg yolk in a large bowl and season with salt and pepper. Using damp hands, combine well, then shape into 2 equal patties.
Step 4 — Cook onion and patties
Heat 2 tsp olive oil in a medium frypan over medium-high heat. Cook the onion, stirring, for 4-5 mins until softened. Remove from the pan. Heat 2 tsp olive oil in the pan over medium-high heat. Cook the beef patties for 3 mins each side or until cooked through (see Make it cheesy).
Step 5 — Serve up
While the patties are cooking, combine 1 tsp dijon mustard and 2 tbs mayonnaise in a bowl and season with salt and pepper. Divide the lettuce among plates and top with the patties, tomato and onion. Drizzle with the mustard mayo and serve with the zucchini fries. Enjoy!
Step 6 — Make it cheesy
If you prefer a naked 'cheeseburger', simply top the patties with grated cheese for the last minute of cooking and cover with a lid to melt.