Preheat oven to 350°F (180°C). In small, heavy-bottom saucepan set over medium-high heat, combine 1/2 cup (125 mL) sugar and 1/4 cup (60 mL) water. Bring to simmer; cook, without stirring, brushing down the side of pan with wet pastry brush to melt any crystallized sugar, for about 10 minutes or until mixture is dark amber colour. 

Divide caramel among six 6-oz (175 mL) ramekins. Working quickly, swirl each ramekin to coat bottom and up the side slightly. Set aside. 

In saucepan, combine milk, remaining sugar and cinnamon sticks. Using vegetable peeler, remove large strips of lemon zest and place in pan (reserve remaining lemon for another use). 

Using small thin knife, split vanilla bean lengthwise; scrape along inside of each half to release seeds. Add seeds and pod to milk mixture; cook over medium heat for about 10 minutes or until small bubbles form around edge of pan. Cover and steep for 15 minutes; strain and discard solids.

In large bowl, whisk eggs and egg yolks until pale. Slowly whisk in warm milk mixture; add salt. Divide evenly among reserved ramekins. Place ramekins in 13- x 9-inch (33 x 22 cm) baking pan. Pour enough boiling water into pan to come halfway up the sides of ramekins.

Bake for 40 to 45 minutes or until custard is just set in the center but still slightly jiggly. Let cool in water bath for 30 minutes. Transfer to rack; let cool completely. Refrigerate for about 4 hours or up to 1 day.

Just before serving, run thin knife along inside edge of each custard to loosen from ramekin. Place small plate over each ramekin and invert to release flan (tap gently to help custard fall onto plate). Pour any residual caramel over custard. Serve immediately.