Line a small bowl with a piece of cheesecloth or set a small fine strainer in the bowl. Peel and finely grate the ginger. Put the grated ginger in the cheesecloth or strainer and extract the ginger juice by gathering the cloth around the ginger and squeezing or by pressing the ginger in the sieve with a small spoon. Transfer 1/2 tsp. ginger juice to another small bowl (discard the rest or save for another use). Stir in the lemon juice and soy sauce. Toss with a batch of vegetables after roasting.
Photo: Scott Phillips