For the Herb Aioli (see note)
180 ml (3/4 cup) mild-flavored oil, such as vegetable, sunflower, or grapeseed oil
1 large egg
30 ml (2 tbsp) freshly squeezed lemon juice (about 1/2 lemon)
30 ml (2 tbsp) chives
30 ml (2 tbsp) chopped Italian parsley
1 large garlic clove
5 ml (1 tsp) Dijon mustard
2.5 ml (1/2 tsp) salt
**Note : Instead of making aioli, you can use store-bought seasoned mayonnaise.
For the Crostinis
1/2 baguette, sliced
600 g (1.3 lb) marinated flank steak or smaller pieces of equivalent weight
Bergeron Fin Renard cheese
Chopped chives
For the Herb Aioli: In the container of an immersion blender or a stand blender, add the egg, lemon juice, herbs, garlic, mustard, and salt. Blend well. Keeping the blender at the lowest speed, pour in the oil in a steady stream—the aioli will form quickly. Scrape down the sides of the container if necessary. If the mayonnaise is not as thick as desired, add up to 60 ml (1/4 cup) additional oil. Taste and adjust seasoning if needed. Transfer the aioli to an airtight jar and refrigerate for up to 1 week.
For the Crostinis: Preheat the oven to 200 °C (400 °F). Arrange the baguette slices on a baking sheet and bake for about 8 minutes, or until the crostinis are lightly golden. (Flip halfway through.) Keep the oven on.
Remove the flank steak from its marinade, if any, and pat it dry with paper towels. Place a grill pan over high heat. Oil the pan and sear the meat on both sides. Transfer the pan to the oven and cook for 12 minutes. Move the grilled steak to a clean plate and cover with aluminum foil. Let rest for 20 minutes. (The steak can be cooked and refrigerated up to 24 hours ahead.)
To serve, spread aioli on the crostinis. Thinly slice the flank steak against the grain and place on the crostinis. Top with shavings of Bergeron Fin Renard cheese and chopped chives. Serve immediately.