For the halva
In a pot, combine the water, sugar, cinnamon stick, lemon zest, rosemary and bring to heat until it just begins to boil.
Remove from the stove and let the syrup absorb the fragrances for 30 minutes.
Strain through a fine sieve and keep warm.
Bring a pot to medium to high heat and add the sunflower.
Add the semolina and stir with a whisk continuously, making sure it does not get burnt, until its color turns dark.
Carefully pour the syrup into the pot and continue whisking until the halva starts to thicken.
Add the raisins and remove from the stove.
Let the halva chill and sprinkle with the roasted pistachio. Serve with the orange sauce and the chocolate sorbet.
For the orange sauce
Place the orange sauce in a small pot and bring to heat until it just begins to boil.
Mix the cornstarch with a little cold water and thicken the sauce with the mixture until it reaches the desired consistency.
Remove from the stove, strain with a fine sieve and let chill.