Place all ingredients, except rhubarb and mint or cilantro, in a medium pot and whisk until smooth. Bring to a simmer and cook 1 minute. (The mixture will be thick, but will loosen once the rhubarb cooks.)
Add the rhubarb to the pot and return to a simmer. Gently simmer rhubarb until just tender, but still holding its shape, about 5 minutes. Remove from the heat, cool to room temperature, and then mix in the mint or cilantro.
Spoon chutney into a serving bowl, cover and refrigerate until ready to serve with the pork.
Preheat an indoor grill or barbecue to medium, medium-high. Brush the pork with the 1 Tbsp. oil; season with salt and pepper. Now lightly oil your grill. Grill the pork 12 to 15 minutes, turning occasionally, or until just cooked through. Rest the pork 5 minutes, and then slice and serve with the chutney.
Note: Two to three medium stalks of rhubarb should yield the diced amount needed for this recipe. To dice the rhubarb, first cut the stalks in half lengthwise. Now cut, widthwise, into 1/4- to 1/2-inch thick pieces.
Options: For another hit of flavour, after brushing the pork with oil, sprinkle and rub it, to taste, with mild or medium curry powder. Now grill as described in the recipe.