Great for summer, quick week-night dinner or a dinner party for friends.
Prepare barbecue (medium-high heat). Brush fish on both sides with olive oil. Sprinkle fish with salt and pepper. In a skillet, add shallots to 1/2 tablespoon of broth. Cook over high heat 1 minute. Add tomatoes to skillet and cook until juices evaporate, stirring occasionally, about 2 minutes. Add wine and tarragon and boil until compote is thick, about 1 minute. Remove from heat and season with salt and pepper. Cover with foil and keep warm. In another skillet wilt the spinach in 2 tablespoons of the broth. When wilted, add the garlic and cover to keep warm. Grill fish until just opaque in center, about 4 minutes per side. Put the summer squash on the grill at the same time as the fish. Transfer to plates. Spoon the compote alongside fish.