Certainly feel free to experiment with food coloring in your strawberry wine but be sure to keep it food-grade and keep it modest to maintain the color within the realm of believability. Food coloring is pretty concentrated so a little dab should do it.
You might want to ask yourself why your wine turned orange in the first place and try to avoid it next time. Orange hues that once were red are most often caused by oxidation and low acidity (high pH), both of which shift wine color from a pink-blue spectrum to the red-orange. I’m also betting that the pigments in strawberries aren’t the most robust and long-lasting out there. You might want to try co-fermenting with a small amount of red grapes next time, or adding some high-color red grape concentrate to back up the natural pigments in your strawberries with some that are more stable in finished wine. A handful of blueberries or blackberries would help, as well as would keeping your pHs below 3.50 or so.
The same caveats and cautions I mention above for food coloring applies to your desire to add vanilla to your Merlot. I would like all readers to be very aware that commercial wineries are not allowed, under any circumstance, to add artificial flavors and colors to their wines. Aromas and spice must come naturally from the grapes themselves and from a short list of approved natural processing aides, like barrels, and cannot be added later. That being said, home winemakers have much greater leeway in what they add to their beverages. I would caution you, as always, to try any additive in small doses before you dose it into a batch, and if you are planning on entering any of your wines in a competition be sure to check with the rules governing artificial additives.
