My luck turned on discovering Jamie Oliver's Rhubarb & Sticky Stem Ginger Crumble recipe, plus stumbling across Felicity Cloake's article 'How to make perfect crumble' on The Guardian's website. The two essential tricks to me are 1) stew hard fruit like my sturdy unforced rhubard for about 5 minutes beforehand to give it a head start at softening, and 2) add oats and a few sprinkles of water to the crumble mix to make it, well, crumbly.
Serves 4-6 heartily
1kg rhubarb, washed and cut into largish chunks
Zest & juice of 1 orange
Other possibilities; 1 tsp fresh grated or ground ginger instead of orange zest, apple juice instead of orange, honey instead of sugar. Jamie Oliver used stem ginger in his recipe but I never have any in.
100g plain flour
100g cold butter
Preheat oven to 180C. Put all the stewed rhubarb ingredients into a pan and bring to the boil with the lid on. Simmer for a couple of minutes with the lid on, and then a couple with the lid off. Spoon into an ovenproof baking dish and put to one side whilst you prepare the topping.
I always make topping in a food processor now. Put the cubed cold butter and flour in the food processor and pulse until it resembles largish breadcrumbs. Stir in the sugar and oats until mixed well. Sprinkle with a little water and stir gently so the crumble clumps together a little. Sprinkle evenly over the stewed rhubarb but do not press down!
Bake for 30-40 minutes, or until the crumble is golden and bubbling. Serve with custard, creme fraiche, or cream.